The long-term unemployed could be forced to work for their benefit payments under plans for the biggest reform of the welfare system in 60 years, the government said on Monday.

Work and Pensions Secretary James Purnell said he wanted to help those on state benefits to return to work rather than relying on long-term handouts.

"The longer you claim, the more you'll be expected to do," he told Sky News. "After a year ... you'll be required to do at least four weeks' full-time work in return for your benefits."

Those unemployed for more than two years or who abuse the system will be made to work full-time, he added. The government will pay the bodies providing the work on the basis of their results.

Under the proposals, more than 250,000 drug addicts will be forced to have medical treatment in return for their benefits, the Guardian reported.

The government hopes to get one million people off incapacity benefit by 2015, Purnell added.

"The way that we want to do that is by offering people more support, but also more responsibility," he told Sky News.

The Conservatives accused the government of stealing policies it first proposed six months ago.

"It would be great news for Britain if the Government is finally planning to introduce the kind of radical change that we have been arguing for," said Shadow Work and Pensions Secretary Chris Grayling. "Once again, it is Conservative ideas that are setting the political agenda."

Liberal Democrat Shadow Work and Pensions Secretary Jenny Willott said the reform was a "step in the right direction".