In a bid to re-establish the Conservative Party's reputation as a tax-cutting party, Iain Duncan Smith has called on the government to abandon its planned increase in National Insurance in April.

In a speech to businessmen in Washington, Tyne and Wear yesterday, the Conservative leader described the one per cent rise in contributions as a "tax on jobs".

He accused ministers of "six years of waste and incompetence" and of having "squandered" the strong economic position it inherited from the previous Tory government.