Two of the Old Trafford stands were evacuated about 20 minutes before the scheduled kickoff at 1400 GMT. Soon after, the game was called off and the whole stadium cleared.
Police investigated the package and used sniffer dogs to search the area, before calling in an army bomb disposal unit.
“A controlled explosion has just been carried out within the stadium by bomb disposal experts at Old Trafford,” Greater Manchester Police said later on Twitter.
The club said in a statement on its website the package had been found in the North West Quadrant, and the match abandoned on police advice.
TV footage showed fire engines arriving at the stadium.
“We don’t make these decisions lightly and we have done this today to ensure the safety of all those attending,” Assistant Chief Constable John O’Hare said in a statement.
United cannot qualify for next season’s Champions League, after Manchester City drew at Swansea City on Sunday. They are sixth in the Premier League table and would move above Southampton into fifth with a draw or victory against Bournemouth.
They play Crystal Palace in the FA Cup final on Saturday, and it is not clear when a rescheduled game against Bournemouth will be played.
In a statement posted on Twitter, the Premier League said it would seek to rearrange the fixture “as soon as practically possible”.
“When it comes to matters of security, it is obviously right that Manchester United and the Premier League place the safety of supporters and employees foremost,” it said.
“It is always the last resort to abandon one of our fixtures.” – Reuters
Original source: Controlled explosion at Old Trafford