Unions have called on Britain's biggest high street chains to withdraw from government programmes that make the unemployed work for up to six months unpaid or face losing their benefits.

The call comes as Sainsbury's, one of the UK's largest retailers, confirmed to the Guardian that it has stopped branch managers from taking on jobseekers under the work experience scheme.

The move follows that of Waterstones book chain, which last week announced it had pulled out of the scheme because it did not want to "encourage work for no pay".

Under the work experience scheme, hundreds of thousands of largely young jobseekers will work in charities and private businesses for 30 hours a week, for eight weeks, without pay, and can have their benefits removed if they withdraw. The government has also introduced a plethora of other schemes, such as mandatory work activity, sector-based work academies, and the community action programme, which can force jobseekers to take unpaid work for up to six months as a condition of their benefits.

The schemes are in operation at more than a dozen well-known chains, such as Boots, Tesco, Asda, Primark, Argos, TK Maxx, Poundland and the Arcadia group of stores run by billionaire Sir Philip Green, which includes Top Shop and Burton.

Shopworkers union Usdaw, which represents more than 400,000 workers in high street retail outlets, said it was currently in discussion with a number of major companies about their involvement.

John Hannett, Usdaw general secretary, said: "Usdaw is not opposed to schemes that genuinely aim to give young people appropriate work experience or help long-term unemployed people get back into work, but schemes should be voluntary, participants should receive the rate for the job, and there needs to be transparent checks and balances in place.

"We are in discussions with the participating companies we have agreements with to re-examine their continuing involvement in the […] various schemes."

Hannett added: "The unemployment crisis is never going to be solved by forcing people to work for nothing. What the country needs is a proper strategy for jobs and growth."

The TUC called for companies to pull out and warned that the government-mandated schemes were encouraging more unpaid work rather than creating actual jobs.

TUC general secretary Brendan Barber said: "While unemployed people may benefit from short periods of work experience, forcing them to work effectively for free for up to six months is not the way to solve the UK's jobs crisis.

"Not only are the high street names involved […] in danger of exploiting participants, the scheme also poses a very real threat to the jobs and pay of existing workers. It is also far from clear whether the placements actually involve any genuine degree of training or work experience that will be of any use to the unemployed taking part.

"The danger is that [this] is simply encouraging employers to continue using unpaid labour when what they should be doing is recruiting unemployed people into properly paid jobs."

Solicitors from Public Interest Lawyers in Birmingham this week issued letters to the heads of 15 companies to make them aware of legal proceedings they have lodged in the high court challenging the legality of such schemes.

Their client, geology graduate Cait Reilly, is currently arguing in the high court that she was made to work unpaid in Poundland, contrary to the forced labour provisions in the Human Rights Act.

Phil Shiner from Public Interest Lawyers said he welcomed the withdrawal of major high street chains from "exploitative" programmes.

"Some major companies are now waking up and turning their backs on compulsory unpaid labour schemes. We have written to a number of major retailers involved in work-for-your-benefit schemes and asked them whether they intend to continue in light of what the Guardian has reported and we have brought to the attention of the courts.

"Whilst our legal actions are against the Department of Work and Pensions, these household brands bear their own moral and social responsibility to ensure that they have nothing to do with these exploitative and ill-judged programmes."

Sainsbury's, which has more than 1,000 stores in the UK, says it only now participates in the work trial programme, in which people work a maximum of 16 hours a week for four weeks in an actual job vacancy, and can pull out at any point without sanction.

Sainsbury's stressed that the work trials were "entirely voluntary" and, unlike work experience schemes, "candidates did not lose their benefits if they didn't participate".

The supermarket added that it had taken on 4,300 employees through the scheme.

Defending its continued participation in schemes that have elements of compulsion, Tesco said: "We take our responsibility as Britain's biggest private sector employer seriously and are playing our part to help tackle unemployment in these challenging times."

Tesco said that over the last four months around 1,400 people had worked for free for a month as part of work experience in its stores, and since the scheme began 300 jobseekers had gained a job with the company.