UNIFORMED police officers are riding on buses in York for the first time after a new spate of attacks on drivers.

Bus managers have warned that the situation is "ominous" and has deteriorated so much that the number seven service to Chapelfields in Acomb, could be withdrawn for the fourth time in just three years.

Their warning was issued after a group of around 20 youths jumped on the bus today and demanded money from the driver before fleeing empty-handed.

On Tuesday afternoon, a driver was assaulted after a youth demanded a cigarette.

And two weeks ago the base of a golf club was hurled through a double-glazed bus window, causing about £500 damage.

The attacks have prompted York police to take the unprecedented decision of putting an officer on services running after dark on Fridays, the night when most incidents have taken place, to deter attacks and reassure the public.

Paul Bell, operations manager for First York, said: "Things are looking ominous."

Mr Bell said that if the company felt they could no longer guarantee the safety of their drivers they would pull the service from the streets again.

"We are prepared to wait and see, but our problem is that we don't want to wait until something serious happens," he said.

"For drivers to be threatened or attacked is just unacceptable."

Drivers have been the victims of a number of attacks in recent years.

One had a brick hurled at him and another was left looking "as if he had gone a few rounds with Prince Naseem".

Inspector Ken Gill, commander of York's west side, said that another option could be CCTV cameras on the buses.

Acomb councillor Tracey Simpson-Laing said that although residents might welcome the police presence in the short term, they would not want it to become a permanent fixture.