The Tories have won the backing of some of the leaders of Britain's biggest companies for their plan to reverse part of the Government's national insurance (NI) increase.

Twenty three business leaders have signed a letter to The Daily Telegraph endorsing the move, saying that it "would protect jobs and support the recovery".

The signatories include Marks and Spencer executive chairman Sir Stuart Rose, Sainsbury's chief executive Justin King, and Sir Stelios Haji-Ioannou, the founder of easyGroup.

Among the other prominent backers are JCB chairman Sir Anthony Bamford, GlaxoSmithKline chairman Sir Christopher Gent, and Next chief executive Simon Wolfson.

Shadow chancellor George Osborne sparked a furious political row when he announced on Monday that he would reverse the 1p increase in NI contributions, set for April next year, for those on incomes under £45,000.

Labour and the Liberal Democrats argued that it was not credible for the Tories to claim they could fund the move through £6 billion of public sector efficiency savings while at the same time arguing that would cut the deficit faster than the Government was planning.

However, in their letter the business leaders warned that raising NI contributions next year could set back the fragile economic recovery at a crucial time.

"The Government's proposal to increase national insurance, essentially placing an additional tax on jobs, comes at exactly the wrong time in the economic cycle," they said.