The Government has been urged to investigate claims that a garda officer may have helped target Louth farmer Tom Oliver who was murdered by the IRA over 20 years ago.
Jeffrey Donaldson of the Democratic Unionist Party said the DUP will be contacting the Government after evidence to the Smithwick Tribunal raised questions over the murder of Mr Oliver.
In July 1991 the father of seven was kidnapped, tortured and shot dead by the IRA.
There was outrage at the time of his killing and his family rejected allegations he had been passing information on republicans to security forces in the Republic.
But a former British agent testifying at the Smithwick Inquiry into alleged garda collusion in the murder of two RUC members in 1989, also indicated that a garda had identified Mr Oliver to the IRA.
Mr Donaldson said his party now planned to lobby the Irish Government on the murder of Mr Oliver following the claims of the agent known as Kevin Fulton.
"Based on the evidence that Kevin Fulton gave to the Smithwick Inquiry, I believe that there have been new revelations that need to be examined to determine whether they would assist the police in apprehending those who were responsible for the murder of Tom Oliver," said Mr Donaldson.
"I am calling on the Irish Government to initiate a review by the gardai of the police investigation south of the Border."