A group of militant Irish nationalists has said it was responsible for the murder of a Northern Irish prison officer as he drove to work earlier this month.
The Belfast-based Irish News newspaper said it had a received a statement from a coalition of dissident groups calling itself the IRA.
The group claims to be the successor of the much larger Provisional IRA which fought British forces in the 1970s and 80s but disbanded after the 1998 Good Friday peace deal.
David Black, 52, was gunned down in a high-speed motorway ambush as he drove to the top security Maghaberry jail, near Lisburn, County Antrim, on November 1.
It was the first killing of a prison officer in Northern Ireland in almost 20 years and the fifth fatal attack on a member of the security establishment since 1998.
"An active service unit of the IRA executed prison guard David Black," the IRA statement said.
"While the IRA never takes this type of action lightly, the IRA has a responsibility to protect and defend Republican PoWs (Prisoners of War)."
The statement said the killing was a direct response to what it said was the "degradation" of Republican prisoners at Maghaberry, where militant nationalists have been protesting against their living conditions and strip-searches.
Four men have been arrested by police in connection with the murder, but all have been released without charge.
Sky News Ireland Correspondent Vicki Hawthorne said of the new 'IRA': "Dissident republican terrorist groups have often worked together.They are known to have shared information and expertise.
"The Real IRA, responsible for the Omagh bomb in 1998 and the murder of police officer Ronan Kerr in 2011, along with the Continuity IRA had been the most active.
"But during the summer the Real IRA and a Londonderry based organisation calling itself Republican Action Against Drugs (RAAD) stated that they had officially joined forces with smaller independent factions. As a group they are now calling themselves the 'IRA'.
"This amalgamation is formalising alliances that were probably already in existence. The group is trying to reclaim the old name of the republican movement, the IRA."