Gordon Brown prepares to impose swingeing tax on gas-guzzling monsters

Drivers of gas-guzzling four-wheel drive vehicles beloved by the affluent middle classes are to be targeted by the Chancellor in this week's Budget.

The cars, scornfully nicknamed "Chelsea tractors" due to their size and increasing prevalence on chic, urban streets, have long been attacked for the damage they cause to the environment and the danger they pose to pedestrians.

Now, owners are to pay a financial penalty. Among measures expected to be included in the Budget is a plan to increase the road tax on these cars, officially termed SUVs - sports utility vehicles. When he unveils his 10th Budget on Wednesday, Gordon Brown is predicted to announce plans to introduce a new top rate of £200 for vehicles emitting more than 250 grams of carbon dioxide per kilometre.

The new rate is likely to affect a number of suburban SUV favourites - including the BMW X5, Jeep Grand Cherokee and Land Rover Discovery.

The move comes after the energy minister, Malcolm Wicks, hit out at the use ofChelsea tractors. "There will come a time when it will be irresponsible for those [4X4s] to be on sale," he said. "There is a crass irresponsibility in some of the large monstrosities people drive."

The move is part of the Government's ongoing plan to cut CO ₂ emissions by 60 per cent before 2050. Road transport is one of the country's most substantial contributors to global warming, with SUVs among the leading offenders.

A record 187,000 4x4s were sold in Britain last year - more than double the number a decade ago. According to the Department of Transport, one in seven cars on British roads is now a 4x4. Originally designed for use off-road and in the countryside, the Chelsea tractor has become a status symbol for everyone from well-to-do mothers on the school run to fashion-conscious footballers.

Fans include TV personalities such as Davina McCall, Tess Daly and Sadie Frost as well as high-profile footballers John Terry, captain of Chelsea, and the Arsenal defender Sol Campbell. Predictably, the England captain David Beckham has one of the largest Chelsea tractors of them all - a Hummer - as well as at least one other SUV among his personal fleet of cars.

Urban drivers of these vehicles have faced increasing criticism, however, being lambasted as "complete idiots" by the London Mayor, Ken Livingstone, and "clinically insane" by the Top Gear presenter Jeremy Clarkson.

In October, the British Medical Journal printed research from the US claiming that SUVs were more dangerous to pedestrians than standard vehicles. Tests showed that people hit by 4x4s were nearly twice as likely to die as those struck by other cars.

Last year, seven police officers were injured in London when the van they were travelling in collided with a 4x4 and came off worse.

Campaigners, led by the Alliance Against Urban 4x4s, want to make SUVs "as socially unacceptable as drink driving", and have begun attaching fake parking tickets to celebrities' Chelsea tractors.

Sarah Teather, the Liberal Democrat MP for Brent East, said: "SUVs in London are a growing and serious problem, putting pedestrians and other road users at increased risk."