An “urgent” inquiry has been demanded into how a “training device” used in an exercise caused a Premier League match at Old Trafford to be postponed.
The match between Manchester United and Bournemouth was called off after the item was discovered close to kick-off.
A controlled explosion was carried out on the device, which police said was accidentally left by a private firm.
Greater Manchester Mayor and Police and Crime Commissioner Tony Lloyd called for a full inquiry into the “fiasco”.
The Premier League match has since been rearranged for Tuesday at 20:00 BST.
Lloyd called the situation “unacceptable” and demanded an urgent inquiry to discover “how this happened, why it happened and who will be held accountable”.
He added: “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.”
United will be refunding all tickets and allowing ticket holders from both clubs in for free on Tuesday night. Manchester United season ticket holders will also be given a credit.
It is estimated this gesture will cost United around £3m.
Bournemouth expect to make an announcement on arrangements for their travelling fans on Monday.
A Greater Manchester Police (GMP) statement read: “Shortly before today’s planned football fixture, staff from the Manchester United ground alerted police to a suspicious item that had been found in the toilets within the North West Quadrant, between the Sir Alex Ferguson stand and the Stretford End.
“Police quickly attended and explosive experts were called in to assess the item, which has been described as an incredibly realistic-looking explosive device.”
The Sir Alex Ferguson Stand and the Stretford End were evacuated and sniffer dogs brought in, reports the BBC.
Kick-off was delayed initially and shortly afterwards the match was abandoned on police advice.
A bomb disposal team carried out the explosion at about 16:30 BST.
Assistant chief constable John O’Hare said: “I am grateful to the Manchester United and Bournemouth supporters for their support and assistance today.
“Following today’s controlled explosion, we have since found out that the item was a training device which had accidentally been left by a private company following a training exercise involving explosive search dogs.
“While this item did not turn out to be a viable explosive, on appearance this device was as real as could be, and the decision to evacuate the stadium was the right thing to do, until we could be sure that people were not at risk.”
Manchester United’s executive vice-chairman Ed Woodward said: “The club takes security very seriously and staff are regularly trained with the police and emergency services to identify and deal with these incidents.
“We will investigate the incident to inform future actions and decisions.”
Just under two hours before the controlled explosion was carried out, an “operation red code” alert had been heard over the public address system, and the players who were warming up had left the field.
Fans were then advised that, because of “the discovery of a suspect package in the north-west quadrant of the ground, the match has been abandoned for today on police advice”.
Supporters who were still in the ground were advised to stay in their seats while the forecourt was cleared of fans who had been in the two stands that were evacuated.
United players were seen leaving the ground shortly after 16:30 BST. BBC commentator Conor McNamara said he saw Bournemouth players and staff boarding their team bus outside Old Trafford around an hour later.
The south coast club flew back to Bournemouth on Sunday night.
Manchester United had started Sunday with an outside chance of qualifying for next season’s Champions League by finishing fourth in the Premier League.
However, Manchester City’s draw against Swansea in their final game means United are effectively out of the running. City are three points clear of their neighbouring rivals and possess a goal difference that is 18 better.
