The government could force people judged too sick or disabled to be employed to do unlimited unpaid work or risk losing their benefits.
The plan would affect those in the work-related activity group claiming Employment and Support Allowance (ESA).
This includes people diagnosed with terminal illnesses but expected to live more than six months, some mental health issues and stroke victims.
According to a report from the Guardian newspaper, the Department for Work and Pensions (DWP) outlined the situation to disability groups and expects to announce its decision after legal changes to the Welfare Reform Bill have made their way through Parliament.
It means work-related activity group (WRAG) claimants could be obligated to perform work experience for charities, public bodies and high-street retailers.
The report explained that in official notes from a meeting in December last year, DWP advisers revealed they were not intending to put a time limit on the work experience placements.
‘When asked at the meeting if there was a maximum duration to the placements, the reply was: "There are no plans to introduce a maximum time limit",' it said.
It continued by saying that when concerns on financial penalties were raised at the meeting, officials said: "Ministers strongly feel there is a link-up to support those moving close to the labour market, and the individual's responsibility to engage with the support.
"Ministers feel sanctions are an incentive for people to comply with their responsibility," it added.
Charities called the plans "very worrying" by claiming enforced work could worsen the health of people affected and that those making the decisions lack sufficient skills to judge the health and capabilities of claimants.