Manchester United: 'Urban climbers' breach Old Trafford security
Four men breached security at Manchester United's stadium by getting on the roof and pitch before a match.
The "urban climbers" were chased by the ground's security staff after they broke into Old Trafford in the early hours of Sunday 4 June, the club said.
It happened hours before Michael Carrick's testimonial game and less than two weeks after a terror attack killed 22 people at Manchester Arena.
The club condemned their actions as "stupid and irresponsible".
The group managed to avoid capture and police said no arrests were made.
A Manchester United spokesman said: "Their stupid and irresponsible actions, especially at such a sensitive time, put last Sunday's game at risk and occupied both club staff and, more importantly, police officers in hours of work to make sure that the stadium was safe to stage the match.
"Such efforts appear to be motivated by a trend for similar actions on social media."
He said the group targeted the stadium shortly after getting on to the roof of a hotel in Manchester city centre.
The Man United incident happened just hours before the One Love Manchester concert at the nearby Old Trafford cricket ground on Sunday evening, and after the London Bridge and Borough Market terror attack on Saturday - with security forces on high alert across the country.
"With over 130,000 people coming into the Old Trafford area on Sunday, the last thing [police] needed was to have their time wasted in this way," the Man United spokesman said.
Officers later searched the stadium to confirm it was safe to hold the match, he added.
Last year, United's home match with Bournemouth had to be cancelled after a dummy bomb used in a security exercise was discovered close to kick-off.