Greater Manchester Police say the suspect device found at Old Trafford on Sunday was left behind in error following a security training exercise.
The device was wrongly signed in by a private company, which ran the training exercise involving sniffer dogs at Old Trafford last Wednesday.
As a result of the error, the match between Manchester United and Bournemouth was called off when the item was discovered close to kick-off.
Greater Manchester mayor Tony Lloyd labeled the situation a “fiasco” and has called for a full inquiry, vowing that someone would be held accountable.
“It is outrageous this situation arose.
“A full inquiry is required to urgently find out how this happened, why it happened and who will be held accountable.
“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.
“It also 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 cooperation during the evacuation, it is unacceptable that it happened in the first place.”
Manchester United executive vice-chairman Ed Woodward defended the club, however, saying he was proud of the way staff acted on Sunday, and said they would take the same action if they were presented with a similar situation in the future.
“The safety of the fans is our No 1 aim at every event we host at Old Trafford. Overall, I’m proud of how our staff responded,” said Woodward.
“The facts are:
“On the discovery of a suspect package, the police and the club worked quickly and closely to identify the threat, make people safe and evacuate the ground calmly and efficiently.
“Fans of both clubs behaved impeccably and the evacuation – the first of its type in the UK – was a complete success.
“Following investigation, the device proved to have been left in error following the training of dog handlers by a sub-contractor.
“The contractor had signed the device as having been recovered along with the 13 other devices at the end of the exercise.
“That device could not have been detected by sniffer dogs on the routine matchday search of the 100 Club, as it contained no explosives and was used in an exercise training handlers not dogs.
“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,” Woodward concluded.