Teenagers riding scrambler motorbikes on parkland could kill a child if they are not stopped, residents fear.

People living near Spindleberry Nature Park and Frys Hill Park in Greater Leys, Oxford, say yobs on noisy motorbikes have been tearing around parkland since the Easter weekend. They have called for improved security.

The parks are close to Pegasus Road, where nine-year-old Ross Doyle was knocked down and killed by a stolen car in December 2000.

Oxford City Council says it has spent £30,000 on fences and kissing gates, which will be installed within eight weeks.

Brian Lester, chairman of Blackbird Leys Parish Council, said: "These motorbikes can go at 50-60mph and if you are walking through Spindleberry Nature Reserve, and they are coming round a blind corner, you could be killed.

"The trouble is catching them. The street wardens are fully aware of it, but they can't do a lot."

Debra Sims, 42, of Pegasus Road, said: "The police are never around to catch them."

Ian Sheppard, city council parks development officer, said: "The aim of the gates is to allow parents with buggies into the park so they can enjoy it, but to keep motorcycles out.

"Unfortunately, if people are determined enough they will still be able to get in."

The Oxford Mail reported in 2002 that the council had spent £10,000 on barriers at Northfield Brook playing field, next to Frys Hill Park, and Spindleberry Nature Reserve. There are also wooden kissing gates at Spindleberry Nature Reserve.

Street wardens' coordinator John Holmes said teenagers had disappeared when they had seen the wardens patrolling.

Sgt Granville Williams, Blackbird Leys area sergeant, said: "I have received complaints and will be looking into it."