An MSP has written to the UK Work and Pensions Secretary over claims that unemployed people are being used as free labour.
SNP MSP John Mason urged Iain Duncan Smith to stop "forcing" people away from employment and into unpaid work experience.
It follows a report in the Sunday Mail newspaper which said job centre managers are under pressure to covert genuine job vacancies into unpaid placements in order to meet targets set by the UK Government. The article suggests that many of the placements will offer no new skills or future job prospects.
Mr Mason asked why job centres appear to have no targets for getting people into work.
He said: "These reports are hugely concerning, and a dreadful indictment of the Westminster government. These people could and should be in paid employment just now, but instead they are being forced to carry out unpaid work experience - even if they're more than qualified for the job.
"Even worse - job centre managers themselves appear to be coming under pressure to convert job vacancies into unpaid work experience places, in order to meet some Westminster government target.
"What the DWP (Department for Work and Pensions) is implementing is effectively a modern-day form of serfdom. I would have expected the DWP and Job Centre Plus to be standing up for prospective employees against unscrupulous employers.
"Iain Duncan Smith needs to explain why job centres have an unpaid work experience target, yet they have no target to get people into work. Surely that is their primary purpose?
"This is just the latest in a series of stories surrounding the welfare policies being implemented by the Westminster government, which range from the shambolic to the downright heartless."
A DWP spokeswoman told the Sunday Mail: "We are very clear that work experience does not replace pad-for jobs but provides people with valuable experience to get a job. It's nonsense to suggest that employers are being discouraged from providing real jobs and Jobcentre Plus takes around 10,000 new vacancies a day for paid jobs."