Police are warning Oxford cyclists to lock up their bikes or risk losing them.

Cycle theft in the city has dropped by almost six per cent in the last year.

But officers of the Oxford Cycle Crime Team are using National Bike Week, which starts today, to warn cyclists about bike thieves.

Pc Jim Abram heads up the team of officers, which was set up last year to stop thieves making off with around 2,000 bikes annually.

There were 1,190 bikes stolen between June 1, 2004 and May 31, 2005 in Oxford, compared with 2,060 between the same period the previous year.

But in Headington, Marston and Barton there has been an increase of almost 30 per cent in the theft rate.

Since Pc Abram's team was created, 40 people have been arrested on suspicion of bike theft.

He said: "Unfortunately, as a city with large number of cyclists, we do suffer from a cycle crime problem and it is something that we are working very hard to tackle.

"However, prevention is often the best cure as the very nature of the offence makes it difficult to catch those responsible.

"I am making a direct appeal to the public to take notice of this advice or you could find yourself with a hefty bill for a new bike."

Pc Abram also called on students leaving Oxford for the summer to make sure their bikes are securely locked away.

Civilian crime reduction officer Nick Gilbert and police community support officers Simone O'Dell and Jacquie Harris will be outside Beeline Cycles, on Cowley Road, from 10am to 2pm tomorrow.

They will provide a free security marking service and will give advice on how cyclists can take action to deter thieves.