The Independent Monitoring Commission report found that former Provisional IRA members are helping dissident republicans work together in their efforts to wreck the peace process and that dissidents pose a major challenge to security forces.

The monitoring group's latest report covered the six months of March to August this year.

The IMC report said: "The overall level of dissident activity was markedly higher than we have seen since we first met in late 2003.

"The seriousness, range and tempo of their activities all changed for the worse in these six months.

"During this period dissident republicans were violent and showed an intent to kill if the opportunity arose."

Last night Mr Spence said: "We (the PSNI] cannot do without the 440 officers of the Full Time Reserve who are well versed in dealing with terrorism and public disorder.

"We have spoken to a number of senior politicians in the NIO and to our Chief Constable and laid our cards on the table - and we have every hope that they will be retained.

"The IMC quite clearly reinforced our long-time view that the threat from dissident republicans continues to rise."

In March the so-called Real IRA shot dead two soldiers, Patrick Azimkar, 21, and Mark Quinsey, 23, outside the Massereene Army base in Co Antrim.

Within two days the Continuity IRA murdered Constable Stephen Carroll, 48, in Craigavon.

The IMC said: "The three murders in March were by far the most serious incidents but there were many others involving extreme ruthlessness."

The IMC cited a string of bomb and gun attacks launched by the groups, noting that many could have easily claimed lives.

IMC spokesman Lord Alderdice said that since the Provisional IRA ended its campaign and effectively disbanded, cases had emerged of former members assisting dissidents.

"There are some indications of individual people on an ad hoc, almost one might say social basis, giving assistance or a handout to people of their acquaintance," he said.

"What is important at this stage is to say that there is no indication of any actual transition of people who were members of one organisation to be members of another organisation."

But while the DUP and Sinn Fein remain divided over when the transfer of policing and justice powers can be completed, the IMC said the move could help undermine dissidents.

"The early devolution of policing and justice powers to the Northern Ireland Assembly and Executive could provide a potent intervention," the IMC said.

"This would not be because the dissidents would be impressed by it.

"It would be because policing and justice would no longer be a point of contention across the political divide, rather, it would be a platform for co-operation against those trying to undermine the peace process.