Cabbies are being secretly filmed by Council officers checking whether they are picking up passengers illegally.

The Telegraph & Argus can reveal that known hot spots are being targeted by undercover officers with video cameras.

The officers then check the tapes and visit offices to see whether fares have been pre-booked.

Dozens of drivers, who were unaware they were being filmed, now face court, heavy fines, disqualification or even imprisonment.

They also face action by the Council which can withdraw their licences allowing them to work as drivers.

Today Councillor Andrew Smith, chairman of the Council's hackney carriage panel, said they hoped to step up the scheme by linking it in to the city's expanding closed-circuit television network.

He said: "I have no problems with video cameras getting evidence which can be used in court.

"We are looking at all possible methods of preventing private-hire vehicles taking fares which have not been pre-booked.

"It is very serious because they are not insured to do it."

He added they are also targeting Hackney Carriage drivers who take private hire customers.

Paul Mills, the Council's Hackney Carriage manager, said: "We have been operating in the hot spots where these offences are occurring and videoing every vehicle which stops there.

"We don't speak to the driver at that stage but look at the film and check on bookings in the various offices.

"A substantial number of drivers are now being interviewed, although none have been referred for prosecution yet."

He said the drivers could be taken to court for driving without insurance and illegally plying for hire.

Linda Smith, secretary of the Bradford branch of the National Private Hire Association, said: "It is just like speed cameras on the motorway. I would urge all drivers to be careful and vigilant."

The move comes as large numbers of cabbies are quitting the trade because of rocketing insurance.