The Caring at a Cost report from Unison shows some migrant care workers have paid more than £20,000 to intermediaries in return for a job before they even arrive.

In return, they can then be housed in overcrowded, substandard accommodation and subjected to appalling racist abuse in the workplace.

The report, based on a survey by Unison of more than 3,000 people who have come to the UK on health and care worker visas, reveals 15% paid money to an employer and 9% to a recruiter or agency before coming here.

Dozens of care staff said they paid fees of above £10,000 in return for the promise of shifts in residential care, in people's homes and other areas of adult social care.

Staff who paid fees to their employer before arriving in the UK gave recruitment (70%) as the top reason followed by visas, flights to the UK, administration/paperwork, training and accommodation.

Around 18% of survey respondents said employers had deducted money from their salary since they'd arrived in the UK. Fees for administration, uniforms, cars, loans, training, hotel rooms, and airport pick-ups were among the reasons given. A smaller proportion (4%) had paid to be released from their contract with a social care employer, despite this being illegal, the report shows.

Problems with pay affected 31% of migrant care staff. This included not getting paid for travel time between visits or sick pay when ill and unable to attend work. Others were paid late, or employers deducted wages without any good reason.

The report shows that 27% of respondents were paid below the legal minimum wage of £11.44 an hour, and 13% of respondents received less pay than non-overseas care staff. Three quarters of those affected said they didn't have enough money, and more than half (57%) were unable to pay their bills.

In addition, the report also highlights the unacceptable conditions in which migrant workers can live, 31% said their employer had provided them with accommodation, but 9% said the housing was either poor or in a very poor state.

Nearly a quarter (24%) of those living in care company accommodation shared a bedroom with other workers. One said 15 people were staying in a one-bedroom flat, and another was among nine sharing a three-bedroom property.

Racism experienced by care staff at work affected 46% of survey respondents. This included verbal insults and physical abuse.

The majority of the perpetrators were someone the staff were looking after followed by other care workers, senior managers, employers, family members or friends. More than a third (36%) said they or a migrant worker colleague had been threatened with dismissal or redundancy for raising issues about their treatment at work.

Unison general secretary Christina McAnea said: ‘These shocking findings highlight widespread exploitation of migrant care workers. They underline the urgent need for reform with a national care service and fair pay agreement in social care.

‘Only when wages rise with the promised fair pay agreement will the care sector be in a better position to recruit and hold on to the growing number of workers needed to deliver quality care to an ageing population.

‘Care staff who come here from overseas are shoring up a crumbling sector. These workers should be treated with respect, not taken advantage of and abused. No one deserves to be treated in this despicable way.'

She added: ‘The government must overhaul the sponsorship system as a matter of urgency. This would help prevent exploitation and drive up standards across the care sector.'