Dawn raids took place across Bradford today as a new police task force went into action to smash a £20 million underworld trade in stolen cars.

Scores of officers swooped on criminals involved at every level of the elaborate chain, from the thieves to the dealers who buy and sell the re-vamped, top-of-the-range vehicles.

The squad was formed by West Yorkshire police in response to a spiralling trend, which surfaced in Bradford three years ago, where gangs burgle homes for car keys in order to take the vehicles.

The stolen cars - usually luxury models like BMWs, Mercedes or Lexus - often have their number plates changed before being sold within the area or shipped elsewhere.

Criminals began committing so-called "Hanoi" burglaries (named after the first police investigation into such break-ins) after improved car security meant they could no longer be stolen without their keys. Burglars also discovered prestige cars fetched a better price than televisions, videos or hi-fis.

It is believed one Bradford gang first began committing "Hanoi" burglaries in the city in July 2000 before targeting outlying areas such Keighley, Halifax and North Yorkshire. It was not long before copycat criminals followed the trend and the offence became prevalent throughout the county and beyond.

So far this year about 1,100 cars have been stolen after burglaries in West Yorkshire.

The value of cars stolen countywide between 2002-2003 stood at £20 million, with £8 million worth of vehicles still to be recovered.

Today's operation centred on about 25 properties in Bradford and Leeds and included the new squad along with the force's Major Crime Unit, drugs and stolen vehicles teams and Operational Support.

At 7am officers wearing full protective kit converged on a tidy semi-detached home in a quiet residential area of Eccleshill.

Within seconds one of them had fitted a hydraulic jack to the door frame while another began to slam it with a battering ram.

On the fourth attempt the uPVC door splintered and gave way to the sound of the burglar alarm and the police squad stormed into the hallway.

Three minutes later a man wearing a T-shirt, tracksuit bottoms and sandals was led out in handcuffs to an awaiting police van.

The 23-year-old, who was already on bail for allegedly handling a stolen car, was ferried to Pudsey police station to be quizzed on suspicion of driving while disqualified.

A police spokesman said officers were focusing on burglars as well as criminals who profited from the illegal trade by manufacturing and supplying false registration plates or buying and driving stolen vehicles.

Detective Superintendent Howard Crowther, who led the operation, said: "Areas and vehicles are specifically targeted and thieves then look for an opportunity to strike.

"They steal the car keys and drive off in the vehicle. They will then look for a similar car and duplicate its registration plate. The stolen cars are then sold."

He said while some unsuspecting victims might buy them in good faith, others were well aware of the trade.

As previously revealed in the Telegraph & Argus, drug dealers can pay as little as £500 for a £30,000 BMW which they drive for a while before simply dumping it or selling it on.

Det Supt Crowther urged people not to buy vehicles without valid documents and warned owners to take precautions.

"No-one would dream of leaving a suitcase containing £25,000 in their drive and the key where intruders could reach them - but that's exactly what they do with their cars. It is vital that householders hide their keys from view," he said.

Anyone with information about car crime should contact Crimestoppers on 0800 555111.