Bangkok: After a brief lull in anti-government protests against embattled Thai Premier Yingluck Shinawatra, chief protest leader Suthep Thaugsuban on Saturday called for a major rally in Bangkok on March 29 to demand reforms before the country holds a fresh election.

The move followed the Constitution Court`s ruling yesterday, which nullified the February 2 poll results.

Suthep, a former opposition Democrat Party MP, is the secretary-general of the People`s Democratic Reform Committee (PDRC), the frontline anti-government protest group.

He urged anti-government demonstrators to hold rallies in their provinces if they were not able to join the demonstrations in Bangkok. He promised peaceful demonstrations and appealed for a big turnout to show the force of reform supporters.

The rally had originally been planned on March 30 but the date was moved a day forward to avoid disturbing the Senate election.

Suthep said that as a warm-up, he would lead marches on Bangkok streets from Monday to Friday to promote and build the momentum for the Saturday rally.

Also on Saturday, opposition Democrat Party leader Abhisit Vejjajiva urged embattled Premier Yingluck and Suthep to hold talks to reach a common ground for holding elections, as the political impasse continues to plague the country.

"I don`t know why Yingluck (Shinawatra) and Suthep (Thaugsuban) cannot hold talks together. It`s time for both to stop demanding any conditions," he said.

Abhisit suggested that Yingluck and Suthep should decide together what should be done before a new election is held, otherwise there would be no guarantee that the next poll would be conducted successfully.

He said that the Election Commission (EC) and the government should hold talks with all parties.

The country`s Constitutional Court had ruled yesterday that the general elections which were held on February 2 were invalid as polls had not been held in 28 provinces.

Thailand has been in political turmoil since mass rallies began in November with protesters demanding an un-elected People`s Council to replace Yingluck`s government.

The protesters accuse Yingluck of acting as a proxy for her fugitive brother, former premier Thaksin Shinawatra, who was ousted in a coup in 2006. He lives in self-exile in Dubai to escape a jail term on a corruption conviction.

The Democrat Party had boycotted the February polls and PDRC supporters had blocked polling stations in the south and in Bangkok to stop voters from casting their ballot.

Suthep said the mass rally would demonstrate that the PDRC won`t accept an election before national reform, and they would continue to protest to oust Yingluck.

Meanwhile, the Bangkok Post quoting a local Thai daily said the Democrats have asked the ruling Pheu Thai party to accept a four-point proposal if it was keen to end the political crisis.

First, Pheu Thai has to unconditionally accept the rulings of independent bodies from the Constitution Court to the national anti-corruption body both in the past and in future.

Second, caretaker premier Yingluck must lead negotiations to find solutions acceptable to all sides and come up with clear reform plans.

Third, Yingluck must not exploit her position as prime minister to exacerbate the problems and lastly, Pheu Thai must adhere to the constitutional monarchy rule.

Meanwhile, four people were injured in a string of grenade blasts in Thailand`s northern tourist province of Chiang Mai that may possibly be linked to the ongoing political crisis though motives were still not clear, police said.

The attacks late yesterday came hours after the country`s Constitutional Court held the February 2 general elections invalid which has upset the ruling Pheu Thai party supporters.

The targets were a seafood restaurant, a petrol station and a brewery.

Four people were hurt but were out of danger, Chiang Mai police said.

Police say the motive could be political or personal. No arrests have been made so far.

In a separate incident, two grenades were lobbed near an anti-government rally in the eastern province of Chonburi last evening though no one was injured.