West Ham United on Wednesday vowed to ban for life any fans found to have taken part in an attack on the Manchester United team bus before their key Premier League game.

The attacked marred West Ham's 3-2 win over the English giants in the final match at the London club's Boleyn Ground on Tuesday night. The match was delayed for 45 minutes because of the incidents.

"It was an extraordinary night full of extraordinary moments in front of extraordinary fans, 99 percent of whom behaved impeccably and were a credit to the club," the club said in a statement.

"However, we are aware that there were some supporters outside the Boleyn Ground who didn't act in an appropriate way when the Manchester United team bus was damaged.

"That was not acceptable and we will work with the police to identify those responsible and ban them for life."

West Ham co-chairman David Sullivan had initially blamed United for the delay to kick-off, saying they should have arrived earlier at the ground.