In September about 1,500 passengers on buses operated by Travel West Midlands were found without a valid pass.

Inspectors checked more than 65,000 people who were using the services during the month.

The firm, which has runs buses across the West Midlands, Coventry and Warwickshire, has warned passengers that they face a fine of at least �10.

Spokesman Phil Bateman said the figure of nearly �20,000 in one month was particularly high.

He added: "If we find a problem, we may ask the policeman on duty to look into it further.

"When we pull them off a bus with a problem with a ticket, other offences can come to light, such as fraud and drug offences."