A fake bomb left over from a training exercise led to the abandonment of Manchester United's final Premier League game of the season, police said.

Bomb disposal experts summoned by Greater Manchester Police carried out a controlled explosion on a suspect package after evacuating the stadium shortly before the scheduled kick-off of United's clash against Bournemouth yesterday.

The item was initially said to be an "incredibly lifelike explosive device" but was later revealed to be a dummy left over from an exercise involving a private firm.

United's executive vice-chairman Ed Woodward promised to carry out a full investigation into how the incident occurred.

Greater Manchester's mayor and police & crime commissioner, Tony Lloyd, called the episode "a fiasco" and called for those responsible to be held accountable.

The match has been rearranged for tomorrow at 8pm, four days before United play Crystal Palace at Wembley in the FA Cup final.

A problematic day for the club was compounded by news of neighbours Manchester City drawing at Swansea to all but secure fourth place, at United's expense.

GMP assistant chief constable John O'Hare said of the Old Trafford incident: "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.

"Whilst 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.

Whilst 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

"Everyone remained calm, followed instructions, and worked with officers and stewards to ensure that a safe evacuation was quickly completed. Those present today were a credit to the football family and their actions should be recognised.

"I would also like to thank all those involved in the operation today for such a professional response, which includes police officers, stewards, MUFC staff, media representatives and commentators and the bomb disposal team."

The device was discovered in toilets in the North West Quadrant of the stadium as the 75,000-capacity ground was filling up. It became apparent there was an issue at around 2.40pm when an announcement was made for security personnel to invoke 'operation red code'.

The Stretford End and the Sir Alex Ferguson Stand, either side of the area where the item was found, were both evacuated. At around 3.15pm, all spectators were told the match had been called off and that they should also leave.

Bomb disposal experts were called in and an explosion was carried out at 4.30pm.

Woodward said: "The safety of fans is always our highest priority. I'd like to thank the support from the police which was first class and the impeccable response from fans of both teams.

"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."

Mr Lloyd, Greater Manchester's mayor and police & crime commissioner, demanded answers over the embarrassing episode.

He said: "It is outrageous this situation arose and 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, 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 cooperation during the evacuation, it is unacceptable that it happened in the first place."

It is understood that, as a goodwill gesture, United will offer supporters a refund as well as a free ticket for the rescheduled game.

A statement from the Premier League read: "We would like to thank Manchester United's staff, the police and other emergency services for all their efforts today as well as rearranging the match for this coming Tuesday.

"Both Manchester United and AFC Bournemouth's management has been extremely helpful in reaching a swift resolution, which is the best possible given today's events."