The car bomb that rocked Birmingham city centre on Saturday night would have caused "very serious loss of life" had the device had detonated fully.
West Midlands police confirmed that it was similar in size to the devices planted outside BBC Television Centre in London and at Ealing Broadway earlier this year.
But this time only the detonator exploded, leaving surrounding cars and buildings untouched and up to 30kg of explosives intact.
It was "probably" the work of the Real IRA, the republican group blamed for the previous attacks, the police confirmed.
The car in which the Birmingham device was planted is a beige Audi coupe, registration number E303 TOV, and police are appealing for help in tracing its owners.
They also want to hear from any potential witnesses who were in the vicinity of the blast, which happened at 2239GMT on Saturday.
The device exploded close to New Street railway station, but no-one was injured despite the area being packed with revellers.
Police immediately ruled out any link to the 11 September attacks - saying a warning was given, but too late to deactivate the device.
Ealier, Chief Constable of the new Police Service of Northern Ireland (PSNI) Sir Ronnie Flanagan indicated that the Real IRA was the main suspect for the bomb blast.
He told BBC's Breakfast with Frost: "Even though it is at an early stage, we do believe it is a dissident grouping - probably that group that is behind this.
"They want to demonstrate that they are still there."
Bomb disposal experts have sealed off a 1,000m area around the site, on Smallbrook Queensway.
Decontamination experts were also called to the scene after passers-by reported seeing white powder come from the car, covering nearby police officers.
But use of anthrax was ruled out. The substance was believed to be stuffing from the car's seats.
The blast came just hours after politicians in Northern Ireland found a way to rescue the peace process, which was thrown into disarray when David Trimble failed to be re-elected as first minister.
Northern Ireland Secretary Dr John Reid said the Birmingham attack was an attempt to prevent the province from finding a resolution.
He told BBC's Breakfast with Frost: "Where there's instability in the democratic institutions then the men of violence will try to wreck this peace process.
"We saw it last night again in the course of the night in Birmingham."
Recent mainland dissident attacks
June 2000: Hammersmith Bridge, London
Sept 2000: MI6 building, London
Mar 2001: BBC Television Centre, London
Apr 2001 Hendon post office, London
May 2001: Hendon post office again
August 2001: Ealing, London
Security in the city is being stepped up, especially with many high-profile guests arriving for the CBI's annual conference, including Chancellor Gordon Brown.
Birmingham was the target of one of the Provisional IRA's worst atrocities when two pubs were blown up in 1974, leaving 21 people dead and scores injured. The pubs stood just 150 yards from the site of the latest blast.
The BBC's Yvette Shapiro said forensic experts were examining the scene and debris to see if it could be linked a particular terror group.
The Real IRA, who are opposed to the IRA ceasefire, are believed to be behind a string of attacks on the mainland in recent months, including a car bomb in Ealing High Street in West London last August. Seven people were injured.