Nationalists opposed to the Northern Ireland peace process have claimed responsibility for last week's fatal shooting at a Dublin hotel, saying it was retaliation for the killing of an ally in 2012.
One man was killed and two others wounded when gunmen opened fire with automatic weapons at a boxing weigh-in, an incident that has become a major issue before this month's general election.
Ireland's justice minister Frances Fitzgerald described the manner of the attack, which happened in broad daylight with children present, just 4 kilometres from central Dublin, as "unprecedented".
In a statement to the BBC, a man claiming to speak on behalf of the leadership of the dissident Continuity IRA group, said its members were responsible, and the attack was retaliation for the fatal shooting in September 2012 of Alan Ryan, another militant nationalist.
"We are not going to stand back and allow drug dealers and criminals to target republicans," the BBC quoted the man as saying. "This will not be an isolated incident."
Fitzgerald said the claims would be thoroughly investigated.
Dissident Republicans do not recognise the 1998 ceasefire in Northern Ireland that was agreed to by the Provisional IRA, which had fought British rule for three decades.
Police have said in the past a number of dissident groups are involved in criminal activity.
Sinn Fein, the former political wing of the provisional IRA, is hostile to the dissident groups and condemned the shooting.
But rival parties claimed the provisional IRA brought in large numbers of automatic weapons similar to those used on Friday to Northern Ireland in the 1970s and '80s.
Senior Sinn Fein member Pearse Doherty denied the legacy of the Provisional IRA was a factor in Friday's attack.
"The (provisional) IRA is gone. The arms have been put beyond use," Doherty said.