The Cabinet is expected to approve later this month new measures to locate the bodies of the "Disappeared" based on information provided by IRA members who were directly involved in their killings.
Sinn Fein president Gerry Adams confirmed today that a British government expert has been assisted by IRA "primary sources" in trying to locate five bodies at different sites in the Republic.
Mr Adams said: "The IRA met the forensic expert seven times over a ten month period".
He said: "There were detailed discussions and specific information was provided on the five outstanding places.
"The forensic expert accompanied by the IRA visited all the sites, and at some of the sites they were accompanied by individuals with primary knowledge," he added.
The Cabinet is expected to be presented with a detailed report urging a fresh approach to finding the bodies based on proposals from the forensic expert.
Last weekend the IRA released a statement defending the murder of Belfast mother of 10 Jean McConville who was killed in 1972.
McConville was abducted from her Divis home in west Belfast in December 1972, shot dead by the IRA and secretly buried. Her body was eventually found on a Co Louth beach in 2003.
The IRA said in a statement on Saturday, which was signed by P O'Neill, that the results of what it called a "thorough investigation" concluded that she "was working as an informer for the British army".
This was a direct contradiction of Police Ombudsman Nuala O'Loan's finding on Friday that there was no evidence Mrs McConville passed information.