The Conservatives have ditched their promise to match Labour's planned spending up to 2011, insisting it is unsustainable in the current economic environment.

In a significant shift of policy, David Cameron said the Government's investment plans were based on "heroic assumptions" about the country's economic recovery.

"Labour's economic mismanagement makes it vital for the long-term health of our economy that we set a new path for restraining the growth of spending," he said.

"That means for the year 2010/11 we need change, not more of the same.

"That means reducing planned government spending growth and not matching Labour's spending plans.

"To be absolutely clear - to stop future tax rises the growth rate of spending in 2010/11 will have to be lower than the growth rate laid out by Labour."

Mr Cameron also warned that Prime Minister Gordon Brown's proposed "fiscal stimulus" was merely storing up tax rises for the years to come.

A £30 billion injection to the economy would mean an 8 per cent rise in income tax later, he claimed.

Mr Cameron said recent forecasts meant the British economy could not withstand previous spending commitments without inflicting bigger tax rises on the public later.

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