More than a million Britons have signed an online petition calling on British Prime Minister Tony Blair to abandon plans for a national vehicle tracking and road pricing system.

The experimental "e-petition", hosted on Blair's 10 Downing Street website, passed the million mark at the weekend after a surge in support.

"The petition gained 300,000 names in five days," said Nigel Humphries of motorist pressure group the Association of British Drivers (ABD).

"Road pricing is just another tax -- and a tax that is unfair, expensive to administer and difficult and inconvenient to collect," he said.

The petition, which closes on February 20, was submitted by ABD member Peter Roberts and calls on Blair to abandon road pricing and instead "concentrate on improving our roads to reduce congestion."

The government is considering proposals to charge motorists for every mile they drive, using satellite tracking technology, with prices depending on the location and the time of day in a bid to counter a growing congestion problem.

Transport Secretary Douglas Alexander told the Times the petition would not deter him from commissioning road-pricing trials.

"The response to this petition makes the case for more debate, not less, on the issue of road pricing," he said.

"It makes me more determined to debate the real issues about how we tackle growing congestion."

Initial estimates suggest a tracking scheme could cost drivers up to 1.34 pounds a mile to drive in the busiest areas at rush hour.

Transport chiefs argue that unless radical action is taken there will be gridlock on some of Britain's roads in 20 to 30 years.

The government has pledged 10 million pounds to fund research into road pricing.

Last December a government-sponsored report on transport led by former British Airways chief Rod Eddington said charging motorists to use roads was the only viable option.