The Continuity IRA has claimed it was responsible for the murder of David Byrne and the wounding of two men at a boxing weigh-in on Friday in Dublin.
While gardaí have said they believe the shooting, in which at least six men were involved, was the result of a drugs feud, the dissident Continuity IRA on Monday said its members carried out the attack.
A spokesman claiming to represent the leadership of the Continuity IRA told the BBC in Belfast that it shot dead Mr Byrne and was planning further attacks on “drug dealers and criminals”.
“A unit of the Continuity IRA was authorised to carry out an operation in Dublin at the weekend, and others throughout Ireland,” he said.
The spokesman claimed Mr Byrne was shot because he had been involved in the murder in Dublin four years ago of dissident republican Alan Ryan.
The latter was a senior member of the Real IRA in the city and was shot dead as a result of a gangland feud in September 2012.
“Although not a member of our organisation, we are not going to stand back and allow drug dealers and criminals to target republicans,” said the Continuity IRA spokesman.
He said there would be more attacks. “The Continuity IRA will carry out further military operations,” he said. “This will not be an isolated incident. Continuity IRA units have been authorised to carry out further operations. More drug dealers and criminals will be targeted.”
The spokesman said the Continuity IRA has been “retraining and re-arming in recent years”.