London - David Cameron on Tuesday began the first major overhaul of his cabinet since it formed in May 2010, with several key ministers sacked or demoted as the prime minister seeks to revive the British government's faltering image.

Kenneth Clarke, who has worked as a minister in every Conservative government over the past four decades, will leave his position as justice secretary to become minister without portfolio.

The 72-year-old denied that his move was an embarrassment, telling reporters: “Being offered a job in the Cabinet at my age - don't be daft.” Former employment minister Chris Grayling will now head the justice department.

Sayeeda Warsi confirmed that she had been removed as Conservative Party chairman, saying on Twitter that she was “signing off” and that it had been “a privilege and an honour to serve my party as co-chairman.”

Also among the casualties was Cheryl Gillan, who was removed from her role as Welsh Secretary.

Downing Street announced that Jeremy Hunt will move from Culture Secretary to Health Secretary, with Andrew Lansley leaving that position to become Leader of the House of Commons.

Former International Development Secretary Andrew Mitchell was promoted to the post of chief whip, responsible for reigning in the Conservative Party's increasingly rebellious members.

But Cameron's centre-right government has not only been at odds with itself as of late. It has also been frustrated by its coalition partner, the Liberal Democrats, on several recent legislative projects, including House of Lords reform and policies toward Europe.

Those with the cabinet's top jobs - including Chancellor of the Exchequer George Osborne, Home Secretary Theresa May and Foreign Secretary William Hague - are assumed to be secure. However, more changes were thought likely in other departments.

Cameron's move to reassert authority over his government comes as the country's economy remains firmly in the grip of a double-dip recession, with Britain's gross domestic product having contracted by 0.5 per cent in the second quarter. -