United Kingdom - A fake bomb left behind following a training exercise was responsible for the abandonment of Sunday's match between Manchester United and Bournemouth at Old Trafford, police said.
Amid a nerve-jangling scare with much of Europe on alert for militant attacks, the device was blown up by army bomb disposal experts after United's world-famous ground had been evacuated.
Greater Manchester Police intially said they had discovered an "incredibly lifelike explosive device".
But later on Sunday the force said the controlled explosion that took place to neutralise the device was carried out on a dummy 'bomb' left in toilets in the Stretford End of Old Trafford on Wednesday.
GMP Assistant Chief Constable John O'Hare said: "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."
The Premier League said the rescheduled fixture, the clubs' last league game of the season, will now be played on Tuesday, with an 20:00 (21:00, SA time) kick-off time - just days before United face Crystal Palace in Saturday's FA Cup final at London's Wembley Stadium.
But the postponement of the original game raises a number of embarrassing questions for United and their security procedures - not least the fact that the device remained in place for four days.
Greater Manchester mayor and police and crime commissioner Tony Lloyd, called the incident a "fiasco" and said those responsible should be held accountable.
An embarrassing incident for United and the security firm was compounded by the vast expense and inconvenience suffered by a capacity crowd of over 75,000 people.
In addition to numerous supporters who travelled from overseas for the fixture, around 3,500 Bournemouth supporters made a round trip of 500 miles (800 kilometres) from the south coast.
"The safety of fans is always our highest priority," said United executive vice-chairman Ed Woodward.
"I'd like to thank the support from the police which was first class and the impeccable response from fans of both teams."
He added: "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."
There was no immediate word from United on refunds.
But the BBC said a source had told them that United would refund ticket-holders from both sides and then offer free entry to them in a move that could cost 3 million ($4 million, 3.8 million euros).
Earlier, the "code red" alert was signalled by police just 20 minutes before the scheduled start of the game.
A club employee found what was described as a mobile phone attached to gas pipes during a routine sweep of the northwest corner of Old Trafford, a source said.
Some players were already warming up on the pitch.
Fans were taken out of the northwest section of the stadium first as military bomb disposal experts rushed to the scene.
Prior to the controlled explosion, the corner where the Stretford End meets the Sir Alex Ferguson Stand was evacuated in an operation which club officials said was carried out quickly and without any injuries.
Remaining spectators in the South and East Stands were judged to be out of the danger area and remained in place but were eventually also told to leave the ground, along with players, management and match officials.
CHAMPIONS LEAGUE HEARTACHE
Kick-off was initially delayed for 45 minutes but police quickly judged that the device presented sufficient threat for the game to be abandoned.
Sunday's incident was the second time in less than a week that United had been involved in a security alert.
Their game at West Ham United on Tuesday was delayed after their team bus was attacked by home fans.
It was a dramatic end to a day in which United supporters had hoped to see their team win and finish in fourth place.
But, with all other fixtures kicking off as planned, Manchester City's 1-1 draw at Swansea City meant United, barring a freakishly huge win on Tuesday, will miss out on qualification for next season's Champions League.
Although Bournemouth have avoided relegation and cannot qualify for Europe, Sunday's match still had significance for the Cherries.
Bournemouth, in 16th place, were looking to complete a league double over United, with the amount of prize money they receive dependent on where they finish in the table.