Three of the people named under parliamentary privilege by the Rev Ian Paisley as having been involved in the Kingsmill massacre have threatened to sue the DUP leader should he make the allegations in public.
The RUC has also opened an inquiry into how Dr Paisley gained possession of what he said was an RUC dossier identifying 20 people allegedly involved in the 1976 attack which left 10 Protestants dead.
After Dr Paisley named the people at Westminster this week, three of those mentioned denied the allegations and warned the DUP leader that if he made such accusations without the comfort of parliamentary privilege he would be sued for defamation. Many of those mentioned, and their legal and public representatives, have accused Dr Paisley of putting the lives of those named in the gravest danger.
Mr Seamus Mallon, the SDLP Deputy First Minister, said he knew many of those named and it was "inconceivable" they would have been involved in Kingsmill or other atrocities.
Mr John Dallat, an SDLP Assembly member for East Derry, said Dr Paisley had given no consideration to the fact that "right across the North there are many people sharing the same Christian and surnames of those he singled out and targeted in Westminster. "At least two of my constituents have names the same as those Paisley read out. I hope he is happy to know that as a minister of religion, presumably interested in family life, he has caused a hell of a lot of anxiety and distress among ordinary decent mothers, fathers and children who have no involvement at any level in politics, never mind terrorism," he added.
"This abuse of privilege needs the urgent attention of the British government. What privilege is there in carrying out an act which could cost an individual his life?" said Mr Dallat.
A police spokesman said an RUC detective chief superintendent had been appointed to head the investigation into the authenticity of the dossier and how it was obtained by Dr Paisley.
