A school has launched an investigation into claims that pupils were kept prisoner on a bus.

Children have told teachers a Network Colchester bus driver trapped them inside his vehicle on Monday afternoon as he passed stop after stop, after collecting them from the Gilberd School.

The youngsters allege they finally made their escape by hitting an emergency button to force open the doors of the vehicle. Senior Gilberd School staff are probing the allegations, and have taken witness statements from pupils.

Network Colchester manager Peter Madden is also investigating. It is believed the driver became concerned over the behaviour of several children as they boarded the bus at the school, in Brinkley Lane, High Woods, Colchester.

A spokesman for Network Colchester said: "We don't want to comment in detail as we don't know a lot more than the school at the moment."