Children are clambering on to the roofs of moving double decker buses in a terrifying new craze in Bradford.

Appalled bus company chiefs fear the practice of 'bus surfing' on schools services could lead to a child being seriously injured or killed.

They have been forced to go into schools to warn children off the craze, while police in Bradford North are stepping up patrols.

Brandon Jones, of bus company First, said they were urgently considering adaptations to the elderly fleet of school buses, to ensure children could no longer gain access to the roofs.

Mr Jones said: "We hope we can put a stop to this before someone gets seriously injured or killed.

"Travelling on top of the vehicle while it is in motion is obviously highly dangerous. This isn't a widespread activity, but neither is it a one-off. We know of incidents involving more than one school."

He said bus drivers are unable to see the top of the double deck vehicles while driving, and the incidents had been discovered when either other pupils or passers-by had raised the alarm.

"The driver has then stopped the bus immediately, without braking too hard."

The company is trying to solve the problem by signing up more schools to its bus monitor system where pupils get free travel on buses in return for keeping an eye on their classmates to stamp out unruly behaviour.

Mr Jones also urged any member of the public who saw an incident to contact police immediately. They should note the exact time and location so that those involved could be traced.

He said other options available to the bus company were to ban individual pupils from school buses, or to withdraw the school bus service from a whole community as a punishment "although that is a last resort."

"What we can't accept is people's safety being threatened," he said.

Detective Inspector Neil Benstead said: "Bradford North police are aware of isolated incidents of this happening. It is very frightening and very dangerous.

"Reports will be rigorously investigated in the light of the obvious danger not only to the offender but also to other road users."

And he warned: "Offend-ers are risking arrest for an offence of public nuisance under common law, they will also be breaching the public service vehicle regulations.

"We are working closely with the bus company and increasing patrols."

Janet Inglis, deputy head teacher at Immanuel CE Community College, said she was aware of the reports in the Thackley area but had no evidence that the culprits were pupils at her school.

"People in this area have seen students doing this but we don't know which school they are from. It's of great concern to us and we are going to make sure we put something into lessons about personal safety."