SINN Fein has rejected allegations in newly released British state papers which claim that a former IRA prisoner and sitting TD was behind 50 murders.
A party spokesman said Dessie Ellis rejects the claims that forensic evidence connects him to a series of killings in Northern Ireland and the Republic.
"Irish Republicans do not attach any value to claims made in secret documents emanating from the British secret services, who were responsible for countless murders in Ireland during the course of the conflict," a spokesman said.
A document in the National Archives in London, released under the 30-year rule, claimed there was evidence against Ellis. It was sent from the British embassy in Washington to officials in London.
"As you know, one of those arrested has turned out on investigation to be Desmond Ellis, who was arrested in Dublin in May 1981 for possession of electronic remote-controlled devices," it said.
"We understand that Ellis is linked by forensic evidence to some 50 murders in Northern Ireland and the Republic."
Mr Ellis was sentenced to 10 years in prison on explosives charges in the 1980s. He went on the run while on bail in 1981, first to Canada and then Buffalo, USA where he was detained for immigration offences.
He was extradited in 1983, and sentenced in Dublin for the explosives offences.
Mr Ellis went on hunger strike for 37 days in 1990 when facing extradition to Britain. He was acquitted in London.
Reacting to the allegations in the British state papers, Sinn Fein described the charges he faced in the UK as "trumped up".
"This is not the first time such unsubstantiated allegations have been made and Dessie Ellis rejects them as he has repeatedly done," a party spokesman said.
"Dessie Ellis has made no secret of his involvement in the Republican struggle over many decades, including within the ranks of the IRA. Dessie has also been an important persuader for the peace process for many years."
Mr Ellis, from Finglas, north Dublin, was elected to the Dail in 2011. He had previously worked as a TV repair man.
Later, Mr Ellis responded to remarks from Fine Gael's Charlie Flanagan after he demanded Sinn Fein deal with the allegations openly.
He said it was ironic for Mr Flanagan to call for a truth commission in light of the allegations contained in British government files.
"I enthusiastically support the establishment of an Independent International Truth and Reconciliation Commission to deal with the legacy of conflict in Ireland," Mr Ellis said.
"I hope Charlie Flanagan will follow up his new found support for such a process with positive action to pressurise his colleagues in Government to act on this."
Mr Ellis added: "Finally, let me say that I am very proud of my involvement in the republican struggle over the years and of the leadership role republicans have played in the peace process, despite the best efforts of nay-sayers such as Charlie Flanagan and his ilk."