The Bill will update existing powers to give local councils more freedom and flexibility to bring in road pricing schemes.

Some 1.8 million people signed a Downing Street website petition expressing opposition to road charging, but Transport Secretary Douglas Alexander stressed that this Bill alone would not provide the legal powers needed for a national road pricing scheme.

He added that any decision on a national scheme could only be taken after local schemes had been assessed and that further, separate legislation - as well as a full public debate - would be necessary. But shadow transport secretary Chris Grayling said that "despite the Government denials, the truth is that this Bill is a Trojan horse for national road pricing".

And Liberal Democrat transport spokesman Alistair Carmichael MP said the Government "must be open and honest with people about its intentions to push forward with road pricing".

The Bill, which effectively paves the way for trials of road pricing to take place, is being introduced despite the 1.8 million name petition. It is expected that any local scheme - which could see drivers paying so much a mile to use congested roads - would be part of a wider package of measures to address local congestion problems and the draft Bill would require that the proceeds from any local schemes are spent on local transport.

Tuesday's Bill also aims to improve bus services. In London, where bus services are privatised but are still regulated, there has been a growing increase in passenger numbers in recent years. But outside the capital, where services have been privatised and deregulated since 1986, there has been a fall in bus patronage.

Mr Alexander said: "The measures we have published will give local authorities the powers they need to ensure that local bus services meet local needs as part of a broader package which will give them the flexibility they need to tackle congestion."

A national road pricing system was advocated - along with other measures - by former British Airways chief executive Sir Rod Eddington in his Government-commissioned report on transport last year. Sir Rod, the Government and technology experts all believe that any nationwide pricing scheme is 10 years away.

Mr Grayling said: "It's now clear that Gordon Brown is as committed to the Government's road pricing plans as Tony Blair has been, despite the petition signed by 1.8 million people and official forecasts that such a scheme could cost up to £60 billion."