As the numbers of bomb attacks in Northern Ireland continues to rise the MI5, and security and military sources, have warned that former Provisional IRA bomb makers have joined dissident republicans.

The head of MI5 revealed that the group has dealt with "more life-threatening investigations” in Northern Ireland that in the rest of the United Kingdom, so much so that they have increased their presence in the North by 33 percent.

In the first eight months of 2010 there were 49 bombings in Northern Ireland. This is to be compared to 22 incidents during the whole of 2009. Also many of the bombs used in the 2009 did not display the level of expertise and sophistication shown in the 2010 bombs.

Next month Bill Clinton will travel to Northern Ireland on a fact finding mission to monitor the fraying security situation.

Jonathan Evans, the director general of MI5, who told the Commons Intelligence and Security Committee: "What was not anticipated ... was the way in which the situation in Northern Ireland had deteriorated. The Service had considerably more what we would call priority, that is life-threatening, investigations in Northern Ireland than we do in the rest of Great Britain."

Last month it was claimed that dissident groups were making plans for an attack on mainland Britain with the Conservative Party conference taking place in Birmingham.

Patrick Mercer, former chairman of the Commons Sub-committee on Counter-Terrorism, said "There are three groups which are planning to do something to catapult themselves into the headlines before the party conference season. They wish to kill ... They have an aspiration to attack targets on the mainland, including the Conservative Party conference."

Yesterday Mr Mercer said that the dissident groups may have obtained the explosives from the Balkans. He added: "What appears to have happened is that hard-line republicans who could never be brought to the negotiating table had been sitting on their hands for the last 10 years waiting for the moment to rejoin their war."

A member of Oglaigh Na hEireann said, during an interview with the Irish News, "There are members of our organization who came from within the ranks of the IRA and had sat back and given Sinn Fein breathing space to make the [Good Friday] Agreement work and achieve their goals. That didn't happen.

"Before we embarked on a campaign we set about acquiring arms and explosives. As the recent upsurge shows, we have the material required to carry out the campaign we have envisaged. It's OK for people to say we don't have the capability. A year ago they said we couldn't even detonate a bomb."

Forensic experts examining a car bomb blast site, Derry City