The intervention by the Taoiseach came as Tony Blair, the Labour leader, was embroiled in a furious row with two left-wing MPs over plans to meet Sinn Fein.
Mr Bruton's comments appeared to lend some support to the accusations made by Gerry Adams, who said yesterday: "The media was briefed that this man was killed in a gunfight and now we are being told that this is not the case. That not only was there not a gunfight, not only did he not fire any shots, but it now appears that he didn't even have a weapon," the Sinn Fein president said.
Mr Adams was supported by John O'Donoghue, justice spokesman for the opposition Fianna Fail party, who said he feared police may have operated a "shoot-to-kill" policy. He demanded an inquiry "at the very highest level".
Scotland Yard is refusing to comment officially on the shooting, but confirmed yesterday via "sources" that O'Neill, who was known as Dermot, was unarmed when he was shot up to 10 times at a guest house in Hammersmith, west London. He died later in hospital.
Clear links between Mr O'Neill and an IRA active service unit have been established, according to intelligence sources in London, although Irish sources have questioned this assertion.
The anti-terrorist officers involved in the raid had been informed, incorrectly, that there were firearms in the guest house. MI5 would have provided the bulk of intelligence, much of which was probably obtained from telephone and electronic listening devices.
Scotland Yard sources were confident yesterday that an on-going investigation by the Police Complaints Authority will exonerate them of any wrongdoing. A police source said: "The officers involved were in fear of their lives and believed the suspect was armed."
Yesterday, it emerged that the five men - one of whom is Mr O'Neill's brother, Shane, 23, - facing a fourth day in police custody are being questioned about the massive Docklands lorry bomb in February in which two people died. Monday's seizures and raids are not, at this stage, believed to be linked with that incident.
Meanwhile, the inquest on O'Neill, who has Irish parents and was born and brought up in London, was opened and his body was released for burial.
As the "shoot-to-kill" allegations mounted, Mr Blair cracked the party whip yesterday with a threat to discipline Labour MPs Tony Benn and Jeremy Corbyn if they went ahead with today's planned meeting at the House of Commons with the Sinn Fein leader.
The proposed visit threw the Labour Party into turmoil after Donald Dewar, Labour's chief whip, issued a blunt warning that Mr Corbyn, MP for Islington North, faced "disciplinary action" if he went ahead with the meeting.
Mr Dewar said in a statement: "I wish to make it very clear that Mr Corbyn is acting on his own behalf and must take responsibility for so doing. The Labour Party is not involved or associated in any way. We utterly condemn his proposed action." The tone made it clear that if Mr Corbyn went ahead, he would lose the Labour whip in the Commons and be unable to stand as a Labour candidate at the next election.
But the decisive action was complicated when it emerged that the room in the Palace of Westminster for the meeting had been booked in the joint names of Mr Corbyn and Tony Benn, veteran leader of the left.
Labour MPs yesterday condemned Mr Corbyn and urged him to pull out of the "private meeting" with Mr Adams - arranged after a news conference to publicise Mr Adams's autobiography was banned by the Commons authorities.
Clive Soley, Labour MP for Hammersmith, where an IRA bomb was discovered and disarmed earlier this year, said his constituents "will not understand" Mr Corbyn's action in "giving a propaganda platform to a party that is soft on violence".Reuse content