Séan Quinn complained in the mid-1980s that sectarian discrimination lay behind the Northern Ireland authorities’ refusal to grant aid to him to develop his business.

Files released today in Belfast by the Public Records Office include correspondence from Mr Quinn, once considered Ireland’s richest businessman, in which he seeks support for a planned cement plant on the Fermanagh-Cavan border.

When the Industrial Development Board would not offer more than 20 per cent –– £3.37 million – of the expected fixed capital expenditure required for the plant, Mr Quinn wrote to the then Ulster Unionist Party leader, James Molyneaux, but to no avail.

While Mr Quinn had provided the development board with a feasibility study, the board took the view that the Quinn Group "revolves around the personality and drive of Seán Quinn" and that if anything happened to him the consequences for the proposed project could be very serious.

Mr Quinn started his business empire by quarrying on the farm in Derrylin, Co Fermanagh, that he inherited from his father. The move to open a cement plant was a major step in the construction of one of the largest industrial manufacturing businesses in Ireland.

In an effort to win over the Northern authorities, Mr Quinn wrote to the former SDLP leader John Hume, in April 1985. He said he had been treated in a "discriminatory manner".

It is not disclosed in the files what type of grant, if any, Mr Quinn received for the cement plant. A request for a comment from the Quinn family was referred to the Aventas Group, which owns the Quinn Group following its seizure by Anglo Irish Bank in 2011. A spokesman for Aventas said he had no information on the matter.

The Quinn Cement website says it began production in 1989. The group built two cement plants. One is now closed but the other is among the former assets that may be bought from Aventas by a group that includes former management of the Quinn Group.