A committee of MPs has criticised the government for failing to take a lead over city congestion charging schemes.

A report by the Commons transport select committee praised the objectives behind such efforts to cut traffic.

But it said it had "serious concerns" about several aspects of the country's first major scheme, which begins in London on 17 February.

On Saturday, a government advisor said that if the London charge was a success, it should be rolled out to other cities.

COMMITTEE'S CONCERNS

London scheme could simply make traffic worse elsewhere Will hit disadvantaged hardest Had no pilot scheme Will take months to establish whether it is a success

The committee said it was worried the government was "not prepared to make a more positive and open contribution to the national debate on congestion charging".

Committee chairman Gwyneth Dunwoody said: "If it believes that charging schemes can make a significant impact on congestion, and can deliver real benefits, it should come out and say so."

The report welcomed charging schemes if they reduced congestion in urban areas and improved public transport.

But it said the London scheme may reduce congestion in the heart of the capital but could simply lead to heavier traffic elsewhere.

And it warned that "schemes which merely displace traffic from a city centre... may cure urban congestion at the price of urban decline, and will lead to problems elsewhere on the road network".

'Concerned'

The London charge could also have a disproportionate effect on low income families and public service workers, it said.

The report questioned why London Mayor Ken Livingstone was implementing the scheme without first carrying out a pilot study.

Alistair Darling should have the courage to stick his head above the parapet and support Ken Livingstone Friends of the Earth

And it said two months - the time period which Mr Livingstone has pledged to establish whether the scheme was a success - was not long enough to say whether it had worked.

Ms Dunwoody said: "Although we support the mayor's objectives, we are concerned about the way the scheme is implemented and the systems which support it."

'Committee is right'

The Greater London Assembly's transport committee has also been monitoring the congestion charge scheme.

John Biggs, chairman of the GLA committee, said it was "imperative" that the scheme worked, so that it could be a blueprint for other national and international schemes.

And he said his committee would continue to assess the scheme in the weeks and months to come.

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Tony Bosworth, Friends of the Earth transport spokesman, said: "The committee is right to support the introduction of congestion charging and to criticise the government for not taking a lead.

"The government's 10-year transport plan relies on cities introducing congestion charging, so Alistair Darling should have the courage to stick his head above the parapet and support Ken Livingstone."

Government advisor David Begg said on Saturday that the area of the charge should be widened to outer London if it was a success.

The government said it would be up to each city council to decide whether or not to adopt congestion charging.

Under Mr Livingstone's scheme, drivers will be charged �5 a day to enter central London between 0700 GMT and 1830 GMT.

He hopes it will reduce traffic by 10% to 15%, and raise at least �130m a year towards improving public transport.