Metro has provided �1.43m to fund the scheme that has seen about 500 buses fitted with up to eight cameras each.

The devices are about the size of a tennis ball and continuously record footage of the driver's cab, bus doors and all seating areas.

Metro said public transport employees and passengers had the right to work and travel without the threat of crime.

"The vast majority of the 200 million bus journeys made in West Yorkshire each year pass without incident," said Metro chairman Councillor Stanley King.

"But by working with the operators to install and operate these cameras, we are ensuring that when vandalism and assaults do occur, we have good-quality images which the police can use in their investigations and as evidence."

Hidden cameras

In recent months, police have used the footage to help secure convictions over anti-social behaviour on the region's buses.

Det Con Kevin Mosley from regional Crimestoppers said the cameras were all about making people feel safer.

"This is excellent progress against the few individuals who disrupt peoples daily journey's in way of damage, assaults or any other type of crime," he said.