More than 9 million motorists look set to be hit with higher road tax under reforms pushed through by the Government.

Motoring and taxpayer groups reacted with anger after ministers admitted that 43 per cent will see their bills rise by up to £245 by April 2010, compared with fewer than a fifth who will be better off in real terms.

It is the first time official estimates have been disclosed of winners and losers from the changes - which ministers insist are designed to punish high-polluting cars rather than raise revenue.

The figures emerged as Treasury minister Angela Eagle hinted that drivers may be offered cash to scrap their ageing gas-guzzlers rather than sell them on.

The tax is likely to be increased on 8.7 million vehicles in 2009-10 - all in the six most-polluting bands. Experts calculate that the Exchequer will have received more than £1 billion in vehicle excise duty (VED) by 2011.

Meanwhile, Downing Street made it clear that the Government has no plans to change the new duty levels following comments made by Chancellor Alistair Darling in a recent newspaper interview.

And a No 10 spokesman dismissed suggestions that Mr Brown had misled the House of Commons over the issue. On June 4, the Prime Minister told MPs that the majority of drivers would benefit from the changes.

However, the spokesman pointed to early comments on May 14 when Mr Brown told the Commons that "the majority of motorists will benefit or pay no more".

The spokesman said: "The Prime Minister made the position clear on May 14 and that is the language that has been used consistently."

The AA said the figures "confirm our worst fears", while shadow chancellor George Osborne accused Prime Minister Gordon Brown of misleading Parliament over the car tax information.

The Liberal Democrats said the Government must have "a death wish", while RAC Foundation said it was "shocking" that the Treasury had taken so long to acknowledge the full impact of the changes, which were first announced in the last Budget.

And The TaxPayers' Alliance said the VED rates are "a cynical tax grab" but Friends of the Earth said the Government should "stand firm" over its car tax plans.

Mr Osborne said: "Gordon Brown appears to have misled Parliament. He said that the majority of drivers would benefit from the changes to VED."

"Now even the Treasury has admitted that just a third of drivers will be better off in 2009, dropping to less than 20 per cent in 2010. This destroys the Government's defence that this is a green tax and in general gives green taxes a bad name."

Ms Eagle insisted there had been no effort to hide the reforms, saying: "It is a pretty bad stealth tax, I would say, given all the publicity that is about."

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