Civil servants and government scientists believed that one of Northern Ireland’s richest men was responsible for serious water pollution – but he aggressively fought the Department of the Environment.

Eddie Haughey, who would go on to become Lord Ballyedmond, engaged in a long-running and aggressive battle with officials over whether his business was responsible for toxic chemicals entering the sewage system.

Officials believed that Norbrook was responsible for toxic water pollution

Mr Haughey, who was a donor to both the UUP and the Conservatives, features heavily in a bulky government file which has been declassified at the Public Record Office in Belfast.

The file deals with trade effluent emanating from his south Armagh business, Norbrook Laboratories, after local residents made multiple complaints of “severe chemical fumes from the drainage system”.

There had also been problems at Bessbrook sewage plant which it was believed were due to toxic substances in the water.

The company’s use of water had increased massively, from 11,000 cubic metres in 1986 to 70,000 cubic metres in 1990 following a major expansion programme.

In a July 16 1991 letter to Mr Haughey, Department of the Environment permanent secretary J Murray asked to install an automatic sampler to test the firm’s discharges.

But Mr Haughey furiously resisted this proposal and his company stopped a departmental scientific officer from entering the site to sample the discharge.

Mr Haughey phoned the department after the scientist, Mr Adamson, had been refused entry to claim that he had been “abusive to his staff”.

A memo from a T N Taylor in the department said: “Frankly, knowing Mr Adamson, I would find that hard to believe.”

A letter from the chief environmental health officer in Newry and Mourne District Council informed the department about its testing of the sewer at the houses – Derybeg Cottages – and found evidence of Xylene, a toxic substance used in laboratories.

A departmental note said that the samples “provide evidence of a highly organic discharge to the sewer which was likely to be coming from Norbrook Laboratories although approximately 22 dwellings and a small car body repair shop are connected to the sewer upstream of the sample point in addition to the Norbrook factory”.

But Mr Haughey fought tooth and nail, threatening legal proceedings against the department, frequently writing to officials to dispute technical aspects of their request and then setting up a meeting with officials.

After that meeting, on September 10 1991, officials concluded that “Mr Haughey would only be prepared to observe the letter and not the spirit of the law”.

But they also conceded that if he initiated court proceedings “an outcome in favour of the department is not assured”.

A September 6 1991 memo from J H McMurray in the department said that Mr Haughey’s behaviour “tends to indicate that his underlying motive is one of avoiding paying the appropriate charges or at least delaying their introduction.

“Alternatively, Mr Haughey’s reticence in accepting that a consent is required or to permit sampling may have something to do with the fact that in samples taken outside the factory organic solvents have been identified.”

He said that sampling on the site “could prove that prohibited substances are being discharged” which would either force Mr Haughey to pay an increased pollution charge or provide pre-treatment works at his own expense.

The documents are contained within volume one of the Norbrook File. Volume two has not yet been declassified so the outcome is unclear.

Lord Ballyedmond was killed in a helicopter crash in 2014.