The boss of the firm that left a fake bomb at Manchester United’s Old Trafford stadium has apologised for making a “devastating mistake”.
Chris Reid of Security Search Management & Solutions Ltd (SSMS) said he wrongly logged the item as found on Wednesday.
The bomb scare led to the postponement of Sunday’s match against Bournemouth.
The club said the device could not have been detected by sniffer dogs because it did not contain explosives.
Old Trafford was evacuated and the match called off after the device was found in one of the toilet blocks.
Mr Reid said he had marked the “mock up of a pipe bomb” as recovered as he had “a similar item which had not been used” in his bag.
He said he was “absolutely gutted” that a lapse in protocol had “resulted in many people being disappointed, frightened and inconvenienced”.
“The mistake is entirely mine, I have to take full responsibility.”
He added the device left behind had a small white label with “training aid” written on it and it was not concealed.
The dummy bomb was initially described by police as an “incredibly lifelike explosive device”. It was destroyed in a controlled explosion.
Speaking outside his home in Biggin Hill, south-east London, retired Scotland Yard police officer Mr Reid said: “To say I am sorry doesn’t seem adequate, but I am.
“There was something found, they dealt with it in the way they should have done. Whether they should have found it earlier is another issue.”
The entire 75,000-seat stadium was cleared and the match was called off, the first time in 24 years that a Premier League match had been abandoned on security grounds.
Manchester United’s executive vice chairman Ed Woodward said the device “could not have been detected by sniffer dogs on the routine match day search of the 100 Club as it contained no explosives”.
He added: “Once a live situation was identified, the club and police had no option but to treat the matter as a potential terror threat; we could not have assumed it was a training exercise error.
“Presented with the same situation in the future, we would take the same action.”
Calls have been made for an inquiry into Sunday’s events.
Greater Manchester Police and Crime Commissioner Tony Lloyd earlier said: “This fiasco caused massive inconvenience to supporters who had come from far and wide to watch the match, wasted the time of huge numbers of police officers and the Army’s bomb squad, and unnecessarily put people in danger, as evacuating tens of thousands of people from a football stadium is not without risk.
“Whilst this in no way demeans the professionalism of the police and stewards responsible for getting the fans out, or the supporters’ calmness and co-operation during the evacuation, it is unacceptable that it happened in the first place.”