German authorities are investigating the possible arrival of 40 Islamist militants among more than 1.1 million asylum seekers who have travelled to the country during the refugee crisis.

The country’s federal police agency, the Bundeskriminalamt (BKA), said it had received 369 reports of possible extremists and found that little over a 10th of the cases warranted further investigation.

The number of suspects is more than double that announced in January, when there had been 213 warnings and 18 investigations were underway.

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“German security officials have indications that members and supporters of terrorist organisations are being smuggled in with refugees in a targeted, organised way in order to launch attacks in Germany,” a spokesperson for the BKA said.

“More attacks by Islamist terror cells cannot be ruled out.”

Several of the Isis militants who carried out the Paris attacks are believed to have passed through Germany on their return from Syria, when they used the Western Balkan refugee route from Greece into Europe travelling on fake documents.

Investigators believe that two more jihadists were meant to join the massacres that killed 130 people but were prevented from reaching their target when they were detained at a refugee centre in Salzburg, Austria.

There is also evidence that Salah Abdeslam, believed to be the lone surviving suspect from the bombings, picked up co-conspirators in the southern German city of Ulm in October last year.

One of his passengers, Osama Krayem, has been charged with “terrorist murder” in both the Paris and Brussels attacks and stands accused of buying the suitcases used for the Brussels Airport bombs and helping Metro bomber Khalid el-Bakraoui.

Another man in the car known only under the aliases Amine Choukri and Monir Ahmed Alaaj, was arrested with Abdeslam and has been also charged with terrorist killings.

Several suspected Islamists have been arrested in Germany since the atrocities. In early February, a 35-year-old Algerian man and his wife were detained at a refugee centre in the town of Attendorn.

The man, a suspected Isis member, reportedly posed as a Syrian when he entered Germany in the autumn.

Days later, a 32-year-old man was arrested in the city of Mainz on suspicion of having fought with the militant group in Syria before travelling to Germany via Turkey.

Shape Created with Sketch. Refugees settle in Germany Show all 12 left Created with Sketch. right Created with Sketch. Shape Created with Sketch. Refugees settle in Germany 1/12 Germany Mohamed Zayat, a refugee from Syria, plays with his daughter Ranim, who is nearly 3, in the one room they and Mohamed's wife Laloosh call home at an asylum-seekers' shelter in Vossberg village on October 9, 2015 in Letschin, Germany. The Zayats arrived approximately two months ago after trekking through Turkey, Greece and the Balkans and are now waiting for local authorities to process their asylum application, after which they will be allowed to live independently and settle elsewhere in Germany. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity 2015 Getty Images 2/12 Germany A refugee child Amnat Musayeva points to a star with her photo and name that decorates the door to her classroom as teacher Martina Fischer looks on at the local kindergarten Amnat and her siblings attend on October 9, 2015 in Letschin, Germany. The children live with their family at an asylum-seekers' shelter in nearby Vossberg village and are waiting for local authorities to process their asylum applications. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity Getty Images 3/12 Germany Kurdish Syrian asylum-applicant Mohamed Ali Hussein (R), 19, and fellow applicant Autur, from Latvia, load benches onto a truckbed while performing community service, for which they receive a small allowance, in Wilhelmsaue village on October 9, 2015 near Letschin, Germany. Mohamed and Autur live at an asylum-applicants' shelter in nearby Vossberg village. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity Getty Images 4/12 Germany Mohamed Ali Hussein ((L), 19, and his cousin Sinjar Hussein, 34, sweep leaves at a cemetery in Gieshof village, for which they receive a small allowance, near Letschin Getty Images 5/12 Germany Mohamed Zayat, a refugee from Syria, looks among donated clothing in the basement of the asylum-seekers' shelter that is home to Mohamed, his wife Laloosh and their daughter Ranim as residents' laundry dries behind in Vossberg village on October 9, 2015 in Letschin, Germany. The Zayats arrived approximately two months ago after trekking through Turkey, Greece and the Balkans and are now waiting for local authorities to process their asylum application, after which they will be allowed to live independently and settle elsewhere in Germany Getty Images 6/12 Germany Asya Sugaipova (L), Mohza Mukayeva and Khadra Zhukova prepare food in the communal kitchen at the asylum-seekers' shelter that is their home in Vossberg village in Letschin Getty Images 7/12 Germany Efrah Abdullahi Ahmed looks down from the communal kitchen window at her daughter Sumaya, 10, who had just returned from school, at the asylum-seekers' shelter that is their home in Vossberg Getty Images 8/12 Germany Asylum-applicants, including Syrians Mohamed Ali Hussein (C-R, in black jacket) and Fadi Almasalmeh (C), return from grocery shopping with other refugees to the asylum-applicants' shelter that is their home in Vossberg village in Letschin Getty Images 9/12 Germany Mohamed Zayat (2nd from L), a refugee from Syria, smokes a cigarette after shopping for groceries with his daughter Ranim, who is nearly 3, and fellow-Syrian refugees Mohamed Ali Hussein (C) and Fadi Almasalmeh (L) at a local supermarket on October 9, 2015 in Letschin, Germany. All of them live at an asylum-seekers' shelter in nearby Vossberg village and are waiting for local authorities to process their asylum applications, after which they will be allowed to live independently and settle elsewhere in Germany 2015 Getty Images 10/12 Germany Kurdish Syrian refugees Leila, 9, carries her sister Avin, 1, in the backyard at the asylum-seekers' shelter that is home to them and their family in Vossberg village in Letschin Getty Images 11/12 Germany Somali refugees and husband and wife Said Ahmed Gure (R) and Ayaan Gure pose with their infant son Muzammili, who was born in Germany, in the room they share at an asylum-seekers' shelter in Vossberg village on October 9, 2015 in Letschin, Germany. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity, and are waiting for authorities to process their application for asylum 2015 Getty Images 12/12 Germany German Chancellor Angela Merkel pauses for a selfie with a refugee after she visited the AWO Refugium Askanierring shelter for refugees in Berlin Getty Images 1/12 Germany Mohamed Zayat, a refugee from Syria, plays with his daughter Ranim, who is nearly 3, in the one room they and Mohamed's wife Laloosh call home at an asylum-seekers' shelter in Vossberg village on October 9, 2015 in Letschin, Germany. The Zayats arrived approximately two months ago after trekking through Turkey, Greece and the Balkans and are now waiting for local authorities to process their asylum application, after which they will be allowed to live independently and settle elsewhere in Germany. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity 2015 Getty Images 2/12 Germany A refugee child Amnat Musayeva points to a star with her photo and name that decorates the door to her classroom as teacher Martina Fischer looks on at the local kindergarten Amnat and her siblings attend on October 9, 2015 in Letschin, Germany. The children live with their family at an asylum-seekers' shelter in nearby Vossberg village and are waiting for local authorities to process their asylum applications. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity Getty Images 3/12 Germany Kurdish Syrian asylum-applicant Mohamed Ali Hussein (R), 19, and fellow applicant Autur, from Latvia, load benches onto a truckbed while performing community service, for which they receive a small allowance, in Wilhelmsaue village on October 9, 2015 near Letschin, Germany. Mohamed and Autur live at an asylum-applicants' shelter in nearby Vossberg village. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity Getty Images 4/12 Germany Mohamed Ali Hussein ((L), 19, and his cousin Sinjar Hussein, 34, sweep leaves at a cemetery in Gieshof village, for which they receive a small allowance, near Letschin Getty Images 5/12 Germany Mohamed Zayat, a refugee from Syria, looks among donated clothing in the basement of the asylum-seekers' shelter that is home to Mohamed, his wife Laloosh and their daughter Ranim as residents' laundry dries behind in Vossberg village on October 9, 2015 in Letschin, Germany. The Zayats arrived approximately two months ago after trekking through Turkey, Greece and the Balkans and are now waiting for local authorities to process their asylum application, after which they will be allowed to live independently and settle elsewhere in Germany Getty Images 6/12 Germany Asya Sugaipova (L), Mohza Mukayeva and Khadra Zhukova prepare food in the communal kitchen at the asylum-seekers' shelter that is their home in Vossberg village in Letschin Getty Images 7/12 Germany Efrah Abdullahi Ahmed looks down from the communal kitchen window at her daughter Sumaya, 10, who had just returned from school, at the asylum-seekers' shelter that is their home in Vossberg Getty Images 8/12 Germany Asylum-applicants, including Syrians Mohamed Ali Hussein (C-R, in black jacket) and Fadi Almasalmeh (C), return from grocery shopping with other refugees to the asylum-applicants' shelter that is their home in Vossberg village in Letschin Getty Images 9/12 Germany Mohamed Zayat (2nd from L), a refugee from Syria, smokes a cigarette after shopping for groceries with his daughter Ranim, who is nearly 3, and fellow-Syrian refugees Mohamed Ali Hussein (C) and Fadi Almasalmeh (L) at a local supermarket on October 9, 2015 in Letschin, Germany. All of them live at an asylum-seekers' shelter in nearby Vossberg village and are waiting for local authorities to process their asylum applications, after which they will be allowed to live independently and settle elsewhere in Germany 2015 Getty Images 10/12 Germany Kurdish Syrian refugees Leila, 9, carries her sister Avin, 1, in the backyard at the asylum-seekers' shelter that is home to them and their family in Vossberg village in Letschin Getty Images 11/12 Germany Somali refugees and husband and wife Said Ahmed Gure (R) and Ayaan Gure pose with their infant son Muzammili, who was born in Germany, in the room they share at an asylum-seekers' shelter in Vossberg village on October 9, 2015 in Letschin, Germany. Approximately 60 asylum-seekers, mostly from Syria, Chechnya and Somalia, live at the Vossberg shelter, which is run by the Arbeiter-Samariter Bund (ASB) charity, and are waiting for authorities to process their application for asylum 2015 Getty Images 12/12 Germany German Chancellor Angela Merkel pauses for a selfie with a refugee after she visited the AWO Refugium Askanierring shelter for refugees in Berlin Getty Images

Hans-Georg Maassen, the head of Germany's domestic intelligence agency (BfV), said the so-called Islamic State was attempting to “send a political signal” by using the refugee route to stoke fears and mistrust in Europe.

“I am not telling you a secret when I say that I am concerned about the high number of migrants whose identities we don't know because they had no papers when they entered the country,” he said.

The number of refugees Germany reached peaks of more than 10,000 a day last autumn but has fallen dramatically in recent months due to the closing of the Greek border with Macedonia and a deal between the European Union and Turkey that allows failed asylum seekers to be deported back over the Aegean.

The reduction in the numbers has eased pressure on Chancellor Angela Merkel, who came under fierce criticism for welcoming hundreds of thousands of those fleeing war and persecution in the Middle East under the slogan “we can do this“.

At least 800 Germans are believed to have joined Isis and other terror groups as foreign fighters, including a man who revealed the reality of life in the “caliphate” in an exclusive interview with The Independent.



Additional reporting by Reuters

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