A controversial “spy-in-the-sky” road tax scheme to cut congestion will be tested out in Essex.

The Government is pushing ahead with a national road pricing plan and has appointed four firms to conduct tests on roads in seven areas across the country, including Essex.

The idea is for drivers to receive weekly or monthly bills, detailing where, when and how far they drove. Drivers on the most congested roads could be charged up to £1.30 a mile.

During the experiments, volunteer drivers will have their cars fitted with special a device which tracks their movements by satellite.

Ministers have suggested the possibility of replacing vehicle tax and even fuel duty with the money raised by a national pricing scheme.

However, Lord Hanningfield, leader of Essex County Council, said he would oppose the scheme unless it was centered around Stansted Airport, which he said was in desperate need of congestion-busting measures.

He said: “We haven’t approved this. I am not keen on road pricing. A lot of people are dependent on cars to get to schools. I am against charging people for just travelling on the roads.”

John Baron, Conservative MP for Billericay, said he was very concerned to hear road pricing could be introduced.

He said: “This feels like another stealth tax at a time when households are already being squeezed.

“There is also an issue of civil liberties. It’s like Big Brother when the Government starts knowing exactly where you’ve been in your car.”

Mr Baron also said he was dubious about the scheme, considering the Government’s bad track record with IT systems.

The Government first introduced the idea in 2004, and said it was considering introducing a “pay-as-you-drive” pricing scheme, with charges of up to £1.34 per mile.

Millions of people objected, with 1.8 million people signing a Downing Street e-petition against the proposal.

The four firms appointed by the Department of Transport to conduct the tests are Intelligent Mechatronic Systems, Sanef Tolling Limited, T-Systems and Trafficmaster.