The head of a security firm that left behind a fake bomb inside Old Trafford, sparking an evacuation of the stadium and the postponement of the Premier League game between Manchester United and Bournemouth, says he takes "full responsibility" for the matter.

Christopher Reid, managing director of Security Search Management and Solutions Ltd., says "the mistake is entirely mine" and that "to say I'm sorry doesn't seem adequate enough."

Reid's company undertook a security training exercise using search dogs at Old Trafford on Wednesday. One of the devices used in the drill was left behind, and discovered by a member of United's staff shortly before the United-Bournemouth match on Sunday. The game was called off and the 75,000-seat stadium was evacuated.

Reid says on Monday he forgot to remove the device after the exercise, as he had a similar one already in his bag.