Residents of Oxford's Rose Hill estate are being asked to be vigilant after bikers have been seen tearing around the area causing a nuisance.

David Penwarden, former Rose Hill and Iffley councillor, said: "During the Christmas break there were motorbikes back on the all-weather pitch making a great mess over it.

"I think they're attracted by the big mounds of earth. I don't see them but you can see all the dirt tracks made."

Motorbikes and quad bikes are being used by youths haring around the nearby Rivermead Nature Park.

Rose Hill councillor Ed Turner said: "It's a perennial problem around here.

"People living adjacent to the recreation ground are sometimes frightened to use their own gardens because there're some very big bikes haring around there."

Mr Turner said the Trax project, a charity based in Osney Mead, Oxford, to help young people build mechanical and other skills was the only legitimate scheme that encouraged biking and should be welcomed, but all illegal bikers must be clamped down on.

He added: "We're not knocking people who want to use motorbikes, but those who want to do it in a very antisocial way."

Police have promised to keep an eye on the area, but say they need people to call them when they spot the bikers, or see where they are later parked.

Sgt Ivan Reaney said: "It's a problem. We do get calls by street wardens but often they've zoomed off. It's difficult to catch up with them, but we know there's a problem."

Insp Chris Tarrant said: "It needs to be reported to us because if we have evidence a particular bike is being used on illegal ground, we have powers to take it. So if anyone spots a bike parked in a garden, that they have seen used illegally, they should tell us."

Anyone with information should call the police inquiry centre on 08458 505505.