He said Sinn Féin would be under pressure to join other parties in recognising Mr Quinn was not involved in criminality when a Dáil debate is held next month.
“The death of Robert McCartney in Belfast three years ago was an outrageous and grotesque act.
“This is actually worse in that the murder of Paul Quinn was premeditated and executed in a manner of military fashion in the style of punishment beatings that were carried out in this area many times during the troubles,” he said.
Mr Kenny was speaking after a meeting with the Quinn family in Castleblayney, Co Monaghan, last night.
Mr Quinn, a truck driver from Co Armagh, was lured over the border to an isolated farm before being savagely attacked in a shed last October.
The Quinn family have consistently maintained Paul was killed by the IRA because of a personal feud with one of its members and have rejected claims by senior SF figures that the incident was linked with fuel smuggling.
“Shortly after the murder of Paul Quinn, SF attributed this to criminal activity. There is apparently very strong evidence now Paul was beaten to death by persons who were or are members of the Provisional IRA,” Mr Kenny said.
“I hope in the debate in the Dáil, that the SF party will clarify any remaining doubts about Paul Quinn being deemed a criminal by them which has been clarified by all parties with the exception of SF.”
Joined by local TDs and councillors, Mr Kenny insisted the murder would be the litmus test for the future of the peace agreement. He also took the opportunity to criticise the Taoiseach and Minister for Foreign Affairs for failing to redraw statements alleging Mr Quinn was involved in criminality.
Brid Quinn, mother of Paul Quinn, reiterated her call for people to come forward with any information relevant to her son’s murder.
“Everybody is born with a conscience and someday their conscience will tell them the right thing to do,” she said.
“The right thing to do is through the courts and no other way.”