Incapacity Benefit will be abolished under the proposals
Unemployed people will be forced to work for their benefits, as part of welfare reforms unveiled by Work and Pensions Secretary James Purnell.
He told MPs that from now on, the longer people claimed, the more the state would expect in return.
The Welfare Green Paper includes plans to scrap Incapacity Benefit and make those jobless for more than two years work full-time in the community.
The Tories back the plans, saying many of the ideas were theirs first.
This shake-up will apply to all 4.5 million people on out-of-work benefits, but is expected to impact most on those on Jobseekers Allowance.
Signed off sick
Mr Purnell told the Commons he aimed to reduce those on benefit by a million over the next seven years.
Claimants will have to carry out four weeks' community work once they have been unemployed for more than a year.
After two years, they will be ordered to work full-time in the community.
Incapacity Benefit claimants will all move to the new Employment Support Allowance by 2013, which ministers hope will be regarded, for all but the most disabled people, as a temporary benefit.
People who have been signed off sick will have a new medical check with someone who is not their own GP.
Drug addicts are also being targeted, with the government expecting them to declare their problem and to embark on treatment in return for benefits.
Mr Purnell said the plans would "transform lives" and help achieve the government's ambition of an 80% employment rate.
"Instead, the longer people claim, the more we will expect in return. At three months and six months, claimants will intensify their job search and have to comply with a back to work action plan," he said.
"Work works and it's only fair that we can ensure that a life on benefits is not an option."
For the first time all parents on benefits will be able to keep their maintenance payments, he said.
And he pledged to "simplify the bewildering complexity of the benefits system".
The Conservatives say they will support many of the proposals, effectively neutralising any Labour backbench opposition.
But shadow work and pensions secretary Chris Grayling claimed the plans were a "straight lift" of those previously put forward by his party.
"Since these are Conservative proposals we will certainly support them," he said.
"I know you will have some difficulties getting them through your own party. Can I assure you we will help you get them through this House even if you have a backbench rebellion to contend with."
The Liberal Democrats have welcomed some elements of the Green Paper, but are reserving their judgment on whether to support ministers.
But former welfare reform minister Frank Field told the BBC's Today programme he doubted the proposals would make any difference.
"The key fault in the old system is being brought into the new system, and that is if you can get through the employment capacity test... you'll get onto a higher rate of benefit," he said.
HAVE YOUR SAY
As long as people are paid a fair wage for their work, why shouldn't they work for benefits?
Peter Hearty, Southend-on-Sea
Mr Field said he had been arguing for 10 years that there should be a single rate of benefit for people of working age who were unable to work. They should be funded via the Disability Living Allowance, not benefits, he said.
"The whole emphasis here, naturally, will be for people not to get jobs but to get onto the higher rate of benefit," he added.
And Labour left-winger Jeremy Corbyn said he was "surprised and disappointed" that the government seemed to be "punishing people for being poor".
In February government welfare adviser David Freud suggested less than a third of the 2.7 million people claiming the benefit were doing so legitimately.
Lib Dem work and pensions spokeswoman Jenny Willott said the government's plans "ignore the disincentive to work that our complex benefit system has created".
"The fact that over half of children living in poverty are in working households is largely ignored," she said. "Reforms must ensure that work really pays or we will see poverty levels rising in Britain."
Jon Sparkes, chief executive of the disability charity Scope, said he had "deep concerns about the tone of these reforms and the target-led ethos underpinning them".
He added: "Disabled people face a myriad of barriers in finding employment, including negative attitudes from employers and inadequate social care support.
"Punitive measures against individual disabled claimants will do nothing to remove these barriers."