WELFARE spending in Britain is "completely unsustainable" Chancellor George Osborne warned as he gears up to deliver tough benefit cuts.

Mr Osborn told the House of Commons that Britain has only one per cent of the world's population but accounts for 7 per cent of the world's welfare spending, and vowed to make the system fairer for taxpayers.

Mr Osborne was making his first appearance at Prime Minister's Questions, standing in for David Cameron who is abroad

The Chancellor is expected to use his Budget on July 8 to set out details of where the axe will fall, with the Tories committed to to cutting £12 billion from the Department of Work and Pensions over the term of the parliament.

He told MPs: "This country faces a very simple choice. We have got 1 per cent of the world's population, 4 per cent of its GDP, but we undertake 7 per cent of the world's welfare spending.

"We can either carry on on a completely unsustainable path or we can continue to reform welfare so that work pays and we give a fair deal to those on welfare and indeed a fair deal to the people, the taxpayers of this country, who pay for it."

Earlier this week, reports suggested the Treasury had asked Welfare Secretary Iain Duncan Smith to find deeper cuts than those announced before the election.

Charlotte Pickles, a former adviser to Mr Duncan Smith and now a senior research director for think tank, Reform, has called for child benefit to be scrapped and some welfare payments to disabled people taxed.

A report by Reform said abolishing child benefit would save almost £5 billion, with poorer families compensated through an increased universal credit payment.

Charlotte Pickles, who was an expert adviser on welfare to Mr Duncan Smith between 2010 and 2012 said the coalition government sought to tackle 'middle-class welfare' but suggested David Cameron's Tory majority administration should go further to ensure that 'social security expenditure is spent on those in need'.