The BBC's Denis Murray: "Wecome but belated development"

The organisation, formed mainly of IRA dissidents opposed to the movement's ceasefire, said it had started "a complete cessation" of military activities from midnight.

Three days after the Omagh atrocity, which killed 29 people and injured over 200 more, the Real IRA declared in a statement that it had suspended its campaign of violence.

The splinter group's new statement, released to the Irish Republic's RTE television and radio network, said the move was being made permanent in line with its "constitution".

That was taken as confirmation that the group had held a meeting of its so-called Army Council to reach the decision.

The BBC's Shane Harrison: "Both governments insist Omagh bombers will still be brought to justice"

The brief statement read: "As a result of intense consultation that has taken place over recent weeks, and in accordance with the constitution of Oglaigh na hEireann [the Real IRA], the volunteers of Oglaigh na hEireann, have determined a complete cessation of all military activity. This cessation will take effect from midnight, September 7."

The BBC's Northern Ireland Correspondent, Mark Devenport, said the declaration could have been motivated both by the tough new anti-terrorism laws and also by "peer group pressure" to end violence.

The BBC's Mark Devenport on why the Real IRA has declared a ceasefire

On Radio 4's Today programme, he said the Real IRA could have been influenced by visits from their former comrades within the IRA on the eve of President Bill Clinton's visit urging them to cease violence, "or face the consequences".

The implication, he said, was that the Provisional IRA was clearly threatening the Real IRA that they had been guilty of treachery.

'Important and positive'

The Real IRA's statement has been greeted by both the Irish and UK governments.

Irish Prime Minister Bertie Ahern called it an "important and positive development" - providing it was permanent.

Bertie Ahern: "Important and positive development"

But he made clear that both the UK and Irish governments remained determined to track down the Omagh bombers.

Echoing Mr Ahern, the UK Government welcomed the statement but said the police would still pursue the Omagh bombers.

The Northern Ireland Office stated: "We welcome any ceasefire including that of the Real IRA and providing that it is complete and unequivocal we shall be watching carefully to see if the Real IRA ceasefire is matched by word and deed."

The declaration also came hours after it emerged that Northern Ireland's First Minister, David Trimble, and Sinn Fein President Gerry Adams will hold face to face talks later this week, which could shape the next phase of the peace process.

One group maintains hostilities

The Real IRA's statement leaves only one known dissident paramilitary Irish republican group, the Continuity IRA, still to declare a ceasefire.

However, according to newspaper reports, it appears unlikely to follow the Real IRA's lead in calling an end to violence.

The Continuity IRA was set up as the military wing of the splinter political group Republican Sinn Fein, which broke away from the mainstream movement in 1986.

It has effectively quashed any hopes that it might declare a ceasefire of its own.

The Continuity IRA contacted Dublin's Irish Times - before the Real IRA's announcement - to indicate it would not be declaring an end to violence.