Gerry Kelly of the Irish nationalist Sinn Fein party accused the militants of extorting money from many dealers in exchange for protection, while those who refuse to pay bribes are targeted.
In their admission of responsibility, IRA members said Kearney had been warned to stop trafficking drugs but "refused to heed this warning and carried on with his activities and as a consequence the IRA made the decision to execute him."
McCrory, meanwhile, was imprisoned last year for trying to rob a Belfast bank.
Also Thursday, police and British Army bomb experts blocked roads and evacuated homes in three parts of Belfast while dealing with suspected bombs. All three alerts regularly staged by IRA splinter groups were declared hoaxes.
The attacks could be timed to coincide with Thursday's start to an international conference in Belfast to woo foreign investment to Northern Ireland, a predominantly British Protestant state that IRA traditionalists want abolished and merged with the Republic of Ireland. British Prime Minister David Cameron is overseeing the two-day event.
The dominant IRA faction, the Provisional IRA, killed nearly 1,800 people in a failed 1970-1997 campaign to force Northern Ireland out of the United Kingdom. The Provisionals disarmed and renounced violence in 2005 in support of the territory's Good Friday peace accord of 1998.
But some former Provisionals have continued to mount attacks in breakaway factions.
Last year, members of four groups, including the Londonderry-based Republican Action Against Drugs, merged into what they call simply "the IRA." Irish media have christened the umbrella faction "New IRA" to distinguish it from a rival splinter group, the Continuity IRA, as well as the faded Provisionals.
This "new" IRA claimed its first killing in November, when a prison officer was shot to death as he drove to work.