Three school buses were taken off the road after a spot check by police found they were unroadworthy.

Faults such as broken fuel pumps forced police officers to order three out of 11 buses checked in Bicester off the road immediately.

They had to be towed away and could not be driven again until they were fixed.

Officers sent two others back to their depots to repair less serious defects including a slightly damaged tyre.

Another police check in Abingdon found two coaches had faults such as broken windscreen washers. The bus owners were ordered to have them repaired within 48 hours or face an immediate ban on driving on a public road.

A minibus was given 14 days to have a more minor fault repaired.

Traffic officers stopped 37 vehicles in the two towns as part of a police operation spanning Oxfordshire, Buckinghamshire and Berkshire.

In total more than 200 vehicles were checked and Oxfordshire's school buses fared better than those used in the other counties. Eight per cent were found to be unroadworthy, compared to an average of ten per cent across the Thames Valley.

Companies operating vehicles that had more serious faults could face prosecution.

Police officers had decided to focus on Bicester and Abingdon after parents and schools there expressed concern about the school transport.

Regional Traffic Inspector Steve Thwaite, of Thames Valley Police, said: "We were acting on intelligence-led information so that explains why our results are so successful.

"The vast majority are run by reputable operators. It is a question of getting them up to standard."

John Mitchell, Oxfordshire County Council's education spokesman, said: "These are essentially minor faults and the vast majority of vehicles are OK. We co-operate with the police and Department of Transport with these random tests.

"It is very important that operators are quite clear that we will not tolerate any inadequacies. Health and safety must be paramount."