The dissident "Real IRA" admitted last night it was responsible for planting a bomb at Laganside courthouse in Belfast.
The admission was made in a call to the newsroom of a Belfast TV station and was accompanied by a recognised code word.
British army experts had defused the bomb left in a van outside Laganside courts complex.
The driver had earlier been forced to transport the device in his white Peugeot van from the north of the city to the centre where he abandoned it before running to tell police.
The device was "unstable" according to the PSNI, and was attached to about 100 litres of petrol.
The design of the bomb and the manner in which it was planted are typical of dissident republican bomb attempts.
The SDLP claimed the incident was a failed attempt by dissidents to distract attention away from the US where political representatives were preparing for President Bush's St Patrick's Day celebrations at the White House.
The van driver said he was forced by three armed men to drive the bomb from his home late on Wednesday night to the courthouse.
Det Chief Insp, Will Kerr said: "The van contained a viable device that could easily have gone off at any time without warning, causing serious injury to anyone who was in the area." The attack was typical of previous attempts by republican dissidents to fire-bomb central Belfast.
Previous incidents have involved similar, small devices which are joined to fuel tanks and fitted with a timer. Other bombs have either been defused or intercepted.
The Laganside complex would have been a high profile target for the bombers. Officially opened by Queen Elizabeth two weeks ago, it is a £20 million gleaming steel and plate-glass structure on Oxford Street, an area which has seen redevelopment and much investment in recent years.
It stands close to the Waterfront hall beside what was the former Oxford Street bus station, the scene of one of the most notorious attacks by Provisional IRA bombers on Bloody Friday in July 1972.
The SDLP's Mr Alban Maginness, a North Belfast Assembly member, said the attack was opportunist and designed "to distract attention from the American visits and attract attention to themselves".
The Lord Mayor of Belfast, Sinn Féin's Mr Alex Maskey, said there was "no place for such activity at all".
The Rev Martin Smyth, the UUP MP for the area, said: "This incident is also another timely reminder of the serious level of threat which continues to exist, against a background of speculation about deals involving reducing security, which would be absolute folly." Mr Nigel Dodds, the North Belfast DUP MP, agreed: "The attack points up the total folly of dismantling security and giving further concessions to terrorists." The Northern Ireland Office Minister with security responsibility, Ms Jane Kennedy, said: "Acts of violence, whether yesterday's murder in south Armagh or last night's attempted bombing in Belfast, must become a thing of the past."