MP Sammy Wilson said his party would "not be turning a blind eye" to the latest developments following Lord Laird's assertion, speaking under parliamentary privilege, that south Armagh "IRA chief" Vincent Traynor "asked to have Quinn executed".

His claim came hours after Independent Monitoring Commission member John Grieve said those involved included members or former members or had associations with members or former members of the Provisional IRA.

But Sinn Fein MP Conor Murphy said Mr Grieve's accusation were "utterly devoid of fact" and evidence rather than speculation was needed to convict Mr Quinn's killers.

Lord Laird also claimed, however, a number of key republicans were consulted and "permission for the execution was given".

East Antrim MP Mr Wilson said his party had requested another meeting with police and would await the outcome of PSNI investigations as well as the next IMC report. His colleague Lagan Valley MP Jeffrey Donaldson said if IRA involvement was proven the party would seek a meeting with Prime Minister Gordon Brown.

Lord Laird said Paul Quinn's brutal murder "resulted from a dispute between Paul and a son of Vincent Traynor, a local IRA chief".

He added: "Paul Quinn and some other youths from the area were involved in activities which did not go down with senior republican leadership in south Armagh, especially as this new breed of republicans are defying the leadership.

"It is now quite clear that Vincent had oversold the case against Paul.

"Several weeks ago Traynor asked the republican leadership, which included Peter and Patrick Quinn - no relation - who run most of the illegal fuel laundering plants in south Armagh for the IRA, to have Quinn executed.

"After consulting with PJ Caraher and his son Michael, who is a well-known murderous sniper, Thomas 'Slab' Murphy, the Provisionals' commander in the area, and Sean Gerard Hughes, known as 'the Surgeon', permission for the execution was given.

"Almost 20 republicans were present at the murder as executioners, look-outs, drivers etc.

"The eight or nine who conducted the execution were dressed in boiler suits and wore surgical gloves.

"All were IRA or former IRA members. It took almost half an hour for Paul to die.

"Every major bone in his body was broken. During the execution he cried for mercy."

Lord Laird told peers during the Home, Legal and Constitutional Affairs debate that the fallout from the murder meant Vincent Traynor was now " number one on the IRA hit list."

He also claimed Thomas Murphy offered to put "a large amount of cash" into Cullyhanna to ease tensions and ordered the community not to talk to police either side of the border.

He said: "Following the murder and the outcry from all parts, a meeting took place in Cullyhanna.

"Slab also ordered that no-one in the community was to speak to the Garda or PSNI. He was taking full responsibility for the incident because it was his close associates involved."