Fianna Fáil's justice spokesman Niall Collins has claimed it is "unacceptable" for Gerry Adams not to tell gardaí the names of the Sinn Féin members alleged to have murdered Brian Stack.

Mr Adams has confirmed he was given the names of the two party members claimed to have been involved in shooting the Portlaoise prison officer in 1983.

Mr Stack was shot by the IRA in Dublin and died of his injuries 18 months later.

Speaking on Monday, Mr Collins said it was an “unprecedented situation” where the leader of a political party knew the names but tried to “wave it off”.

He said it was “not acceptable or good enough” and was a reminder of how “toxic Sinn Féin are”.

The party’s justice spokesman said no other party leader would be allowed to get away with such a situation.

“We know senior frontbenchers within Sinn Féin seek to try and dismiss the murder of Brian Stack as a mere footnote and sought to justify that. That is not acceptable and shows how unacceptable Sinn Féin are for Government.”

Mr Adams has confirmed he was given the names of two senior party figures alleged to have been involved in the murder of Mr Stack. He said that he has not spoken to the two people involved about the claims.

Speaking on Monday, Mr Adams said he had met Austin Stack, a son of the murdered officer, and other family members on occasions.

“He gave me a number of names, for example, he gave me the names of Republicans who had been in Portlaoise prison at the time when his father was there,” he told RTÉ Radio. “He did give me the names of two members of Sinn Féin who he said had involvement and told me he had been given those names by the gardaí.”

Mr Adams said he had told Austin Stack it was improbable he or members of his family could meet members of the IRA involved in the crime. He had spoken to one republican but this man said he had nothing to do with the crime and did not wish to meet Mr Stack.