Dissident republicans remain highly active and dangerous, according to the Independent Monitoring Commission.
It said the threat was "very serious" but they were not able to mount a campaign like the Provisional IRA.
Its latest assessment of paramilitary activity covers from 1 September last year to the end of February 2010.
It reflects recent police warnings that the threat remains severe, and that dissidents have improved their bomb-making abilities.
Dissidents have been responsible for a number of attacks in Northern Ireland this year, including bombs at Newtownhamilton police station and Palace Barracks in Holywood.
The commissioners said the Real and Continuity IRA were continuing to recruit and train members, acquire weapons and target potential victims, with police officers the main focus of their activities.
But the report added there is no evidence to suggest a reappearance of something comparable to the Provisional IRA's campaign of violence.
In its 23rd report issued to the British and Irish governments, the IMC said mainstream organisations continued to follow a peaceful path.
The commission said dissidents lacked significant local or international support, and did not have comparable resources in terms of personnel, money, organisation and cohesion, or range of weaponry and expertise.
"In particular, the range and nature of RIRA's (Real IRA) activities in the six months under review were, by any yardstick, a very serious matter," said the IMC report.
"However it is important to point out that this is in no way a reappearance of something comparable to the PIRA (Provisional IRA) campaign."
The report noted that former members of the Provisional IRA were helping dissident groups, but said this was on an ad-hoc basis by a small number of people.
The IMC said that while members of dissident groups were co-operating, it did not believe the organisations had managed to come together to form a united front.
In its previous report, the IMC said some former members of the Provisional IRA were assisting dissident groups by providing technical expertise.
Commenting on the report, Secretary of State Owen Paterson said that the report "has acknowledged the very real and serious threat from dissident republicans".
Mr Paterson said: "The IMC report that the criminal justice system offers a potent response to paramilitaries, particularly now it is owned by and accountable to the people of Northern Ireland."