Sinn Fein President Gerry Adams told Taoiseach Enda Kenny he believes the remaining bodies of the Disappeared are buried in counties Meath and Monaghan.
Mr Kenny says he has met with the families of the Disappeared, who were abducted and murdered by the IRA and buried in secret locations.
The remains of seven victims have yet to be located.
The Taoiseach also said he had spoken to Mr Adams regarding the issue and asked him if he could offer any assistance, given Sinn Fein's links with the IRA.
"He did suggest from the knowledge that he had that the remains of the seven may be in county Meath or county Monaghan," he said.
Mr Kenny again appealed for anyone "who might have remorse" with information on the location of the bodies to come forward.
The Taoiseach said somebody made a decision to carry out the murder.
Mr Adams said previously he had worked closely with the commission set up to locate the bodies and has asked for anyone with information to come forward.
The Sinn Fein President is repeatedly accused of being a leader of the IRA and has been accused of ordering the murder of Belfast mother-of-ten Jean McConville.