IAIN Duncan Smith insisted there was a "once in a lifetime opportunity" to reform welfare as he made clear benefits would be slashed again in the next parliament.

The Coalition will, by 2015, have cut the welfare bill by £18 billion with another £10bn of cuts in the pipeline for the following year; the annual cost of benefits is around £200bn, representing one-third of all Government expenditure.

The Work and Pensions Secretary said by reducing the welfare bill, the Coalition would focus on how to transform people's lives.

Hailing his proposed Universal Benefit, which will replace a raft of other benefits, he described it as "the most extensive shake-up of the welfare system for years" – and warned unemployed claimants against shirking work.

"If you won't work with us to find work, you will lose your benefit," declared the former Tory leader.

He went on to accuse Labour and trades unions of sabotaging a work experience scheme designed to help young people gain valuable insight into employment.

"The unions, with Labour support, have attacked the programme," said Mr Duncan Smith. "They are trying to frighten off businesses, even going as far as calling it 'slave labour'."

"Just how out of touch they are? Labour and the unions would rather have the young people of this country living off state hand-outs, instead of being employed," he added.