An Irish Republican Army faction has claimed responsibility for killing a reputed member of a drug-dealing gang in a machine gun attack on a Dublin boxing pre-match event, and is threatening to kill more criminal rivals.

The Continuity IRA issued a statement Monday to the BBC in Belfast saying its members were responsible for Friday's killing of 33-year-old David Byrne. Police say six people committed the attack, including three disguised as police officers armed with assault rifles.

In the statement the outlawed faction — one of several small groups still plotting violence in neighboring Northern Ireland — accused Byrne of involvement in the 2012 Dublin killing of a senior figure in another IRA faction.

Police say IRA factions are heavily involved in Dublin's underworld and supply weapons to rival gangs.