The Irish Republican Army's (IRA) ruling Army Council is no longer operational and the guerrilla group does not pose a threat to peace in Northern Ireland, an independent watchdog said.

The IRA was responsible for more than half of the 3,600 sectarian killings in the British-ruled province during three decades of violence that largely ended with the 1998 Good Friday Agreement. A agreement last year by political foes to share power in a regional government cemented the 1998 accord. "Now that that campaign is well and truly over, the Army Council by deliberate choice is no longer operational or functional," the Independent Monitoring Commission said in a report.

"We do not believe that it (the IRA) presents a threat to peace or to democratic politics," Northern Ireland's official arms watchdog said.

The IRA pledged in 2005 to disarm and pursue its goal of a united Ireland through peaceful means, but its continued existence has remained a concern among unionists who favour British sovereignty in Northern Ireland.