Hi-tech offensives are being planned to deter the thousands of motorists who drive off from Oxfordshire's petrol stations without paying each year.

"Drive-offs", or bilkings as they are known by police, cost garages across the county thousands of pounds in lost revenue. This loss is often passed on to the consumer through higher fuel prices.

Last year, as petrol prices soared, 729 incidents were reported to Oxford police, and officers estimate this could be as little as 25 per cent of the real figure.

Pc Peter Hickman, who is co-ordinating a crackdown on bilking in Oxford, said that poor quality CCTV tapes often meant garages could not be sure an offence had taken place, or give the police a proper description.

But in a joint operation with police, the BP service station at Oxford's Wolvercote Roundabout and the Sainsbury's petrol station in Kidlington have seen a drop in crime since installing new cameras.

Pc Hickman said that after installing the automatic number place recognition (ANPR), the BP garage saw offences drop by about 75 per cent.

He said: "Your number plate is photographed as soon as you come on to the forecourt, and if it is recognised on the system, the cashier is alerted and switches off the pump.

"We are having a conference with garages in the Oxford area to talk about buying a system that will link them up. We have got two systems in mind."

Kevin Morton, duty manager at Sainsbury's in Kidlington, said: "It has helped. The amount of people we have driving off varies from week to week, but it is down."

Oxford police have had 281 reports of bilkings so far this year, but the detection rate is up from three per cent in November to 12 per cent now.