Highly qualified staff, with up to 10 years experience in their own countries, are lured to the UK by agencies promising lucrative contracts in NHS hospitals. But when they arrive in the UK they are given student visas and jobs as care assistants in private nursing homes.

Students visas ban them from working more than 20 hours a week. A report in the Sunday Herald has revealed cases which include nurses living in appalling conditions and forced to work up to 60 hours a week to pay £5000 agency "placement fees", accommodation costs and a £1200 "adaptation course" introducing them to British nursing techniques and procedures.

Despite such heavy costs some have to return to their country of origin and re-apply for UK employment once they complete the adaptation course, under immigration rules.

The report cites the cases of two female nurses forced to stay in an unheated warehouse on an industrial estate near Glasgow. As they had no money for taxi fares and did not understand the time table, they had to walk for an hour and a half to get to work each day. Another highly qualified male nurse has been surviving on £5 a week because of debts to the recruitment agency and his landlord. One male nurse moved to Scotland from an English nursing home after he was "sold off" to another agency without his knowledge.

The report said staff have been sleeping and showering in nursing homes because they cannot afford to stay anywhere else. They get a bed only when one of the elderly residents dies. The identities of the nurses have not been disclosed because they fear they will lose their jobs.

Sofi Taylor, of the Overseas Nurses Network, said: "I know of trained nurses who have paid five years' salary to come to the UK because they were told they would have a better life. But when they get here they realise the contract from the agency is not worth the paper it's written on."

"We've had people being paid less than the minimum wage at £3 an hour, people told they will have to enrol as students, and others told that if they left the job they would have to pay £2000 and be forced to go home. One woman worked for a month without pay."

Other cases include a group of overseas nurses who were told they would be guaranteed jobs, but when they arrived they were placed in a college to study English. "This is a scam and it is being allowed to happen," said Taylor. "It's bonded labour, because you are being forced into terrible situations as part of a contract. If you can't fulfil it, you are no longer welcome in the UK."

Dr Bridget Anderson, of Oxford University's Centre on Migration, Policy and Society, which will publish the ILO research, said she had come across "horrific" examples of abuse in Scottish care homes. "Typically, they have borrowed up to £10,000 to come to the UK on the understanding that they will pay it back when they get their job," she said.

"What they find instead is that they are abused and paid less than their colleagues, but can't leave because the visa ties them to the job. If they leave, they have to go home."

Anderson accused the foreign nursing agencies and Scottish care homes of "trafficking" the nurses to the UK, where they were open to abuse. "People trafficking is associated with sex and women working in prostitution, but these nurses are effectively victims of trafficking too. We're all using the services of people in these awful situations."