The IMC will today report on the highest threat posed by dissident republican groups since the monitoring commission first began its work more than five years ago.

According to one source, the threat is assessed as consistently more serious now than at any other time since 2004.

The assessment compiled by Lord Alderdice, John Grieve, Dick Kerr and Joe Brosnan is being published today.

It follows the Real and Continuity IRA gun attacks at Massereene Barracks and in Craigavon in March in which two soldiers and a police officer were shot dead.

The report also follows the recent bomb incidents at Forkhill and in east and north Belfast.

The pages of the IMC assessment will be read for any information pointing to greater co-operation between the dissident groups and whether help is being provided by former mainstream IRA members.

One source said there has been “no substantial movement of people” from the IRA into dissident ranks, but there is an assessment of individuals providing expertise.

Alongside the growing threat, the Continuity IRA and Real IRA are becoming bigger organisations.

In this latest assessment the Independent Monitoring Commission will also report on the loyalist decommissioning in June — a move almost derailed by the dissident attacks three months earlier.