David Cameron has strongly defended his policy of reducing the deficit as soon as possible and scrapping part of the government's proposed National Insurance increases if he wins power.

Interviewed by Today presenter Sarah Montague he said that tackling government debt, currently running at £167bn, should be a priority in order to avoid what he called the risk of a "Greek-style catastrophe".

But he accepted that Conservative proposals, which include freezing public sector pay for a year and ending the provision of child trust funds for richer families, are "still not enough to fill the hole".

Mr Cameron's comments come after 23 business leaders signed a letter to the Daily Telegraph endorsing the move, saying it "would protect jobs and support the recovery". The signatories include Marks & Spencer executive chairman Sir Stuart Rose, Sainsbury's chief executive Justin King, and Sir Stelios Haji-Ioannou, the founder of easyGroup.