Ulster Unionist leader Mr David Trimble today said there was "good reason" to suspect the 19-year-old Catholic man killed in Co Antrim yesterday was murdered by republicans.
The former First Minister suggested the fatal shooting of Mr Ciaran Cummings as he waited at a roundabout on the outskirts of Antrim town could be linked to drugs.
Sinn Féin described the allegation as "completely unsubstantiated" and said it was "clearly a sectarian killing".
Mr Trimble, speaking on RTE's Morning Ireland,said: "Quite a few of the murders of Catholics over the last number of months have been by republicans. I think we have got to bear that in mind.
"I know that yesterday's statement came from one of these dissident loyalist groups but there is good reason to suspect that republicans were behind the Antrim murder.
"It goes back to drugs - a number of the various forms of racketeering. A number of murders of Catholics by republicans have been of people who have not been sharing the profits of their business with republicans the way they feel they ought to," he said.
A caller claiming to represent the Red Hand Defenders claimed responsibility for the killing yesterday by telephone to a Belfast newsroom.
A Sinn Féin spokeswoman said today: "It was a sectarian killing, there can be no doubt it was. Even the RUC themselves are saying it was a sectarian killing.
"It is appalling that this young man's family are getting dragged into the difficulties facing the peace process by David Trimble."
As the Parades Commission today decides whether to overturn its Drumcree ban, Mr Trimble also said the republican movement was responsible for increased violence in Belfast.
PA