Overseas nurses face racism and exploitation while working in the UK, a report has found.
The NHS was praised by overseas nurses
The report, from the Royal College of Nursing (RCN), says nurses are charged "extortionate and illegal" fees to come and work in the UK.
Some nurses described their working conditions as "slavery", with the independent sector coming under particular criticism.
In contrast, many nurses praised the NHS for the support it had given them.
The RCN is calling for action to prevent overseas nurses being exploited or being the target for racism in the NHS and private sector.
It also wants better adaptation procedures, pay and conditions.
'It's not worth it'
Nurses told RCN researchers the colour of their skin had affected how colleagues in the UK treated them, either through "crude racism" or because they were "singled out for negative attention".
One nurse from Zambia said: "I think you are made to realise what colour you are, something that you never thought about at home."
A 52-year-old South African nurse said: "We tend to keep our skills in our pockets and watch.
"To be honest with you, I'm counting the days when I'll be going back home. It's not worth it to work here as a nurse."
One nurse's story
Tessy Joseph, a cardiothoracic nurse in Delhi, India, was approached by the manager of a UK nursing home.
She was asked to pay 90,000 rupees (£1,215) to cover flight and administration costs.
She told BBC News Online: "They told me I could work as a nurse here.
"But when I came to the UK, I was working as a carer in a nursing home.
"They said I could get a place on an adaptation course as soon as I got here, but I had to wait for 10 months."
Tessy then saw an advert for Oxford's John Radcliffe hospital, which she said offered much better educational opportunities.
She now works there as a cardiothoracic nurse.
She said: "I'm much happier now, happier than when I was working in the nursing home."
Almost 70 nurses, with an average of 14 years' experience in their home countries, were interviewed about their experiences.
Nurses told how they were illegally asked to pay thousands of pounds to come and work in the UK.
They were asked to pay for flights, administration fees, and for adaptation courses.
These courses, which are supposed to be free, train overseas nurses to work in the NHS. If they complete them successfully, they can register as a nurse in the UK.
But after paying for training, many nurses found themselves working as low-paid carers in independent sector care homes, unable to gain places on adaptation programmes.
Many believed that they were just being used as "cheap labour", and that their employers were delaying the registration process so they could keep them on lower pay rates.
A Nigerian nurse said: "I was recruited from home, not from people here but a nursing recruitment agent back home, which they sent us here for a nursing home.
"When we came here it was all fake, so we had to find our own ways, we had to like start applying to NHS, all the hospitals...for adaptation."
And a Zambian nurse said: "Agencies that recruit the nurses from back home they should be able to tell us what sort of areas they're going to send us to so that we are aware in advance."
She said the existing situation meant overseas nurses found themselves in low-paid, unskilled posts such as working as a "tea-maker in a nursing home".
Dr Beverly Malone, general secretary of the Royal College of Nursing, said: "Over the last few years, the RCN has represented hundreds of internationally recruited nurses who have faced exploitation and discrimination - but we know this is just the tip of the iceberg.
"Many more are too afraid to take action against their recruiters or employers."
She added: "We know of cases where nurses have their passports taken away and are threatened with deportation if they complain or try to leave.
"This is no way to treat human beings."
Dr Malone said: "It is clear from our report that that whilst recruitment practices in the NHS have improved significantly in recent years, some parts of the independent sector are still lagging behind.
"Some situations are appalling, leaving the nurses to work without any proper induction and under miserable conditions."
Sarah Mullally, the government's Chief Nursing Officer said: "There is no place for discrimination in the NHS on the grounds of ethnicity, gender, sexual orientation, disability, religion or age.
"Nurses legally recruited from abroad to work in the UK are protected by UK employment law in exactly the same way as all other employees."
She said guidance had been produced earlier this year for the NHS and independent sector outlining how overseas nurses should be helped to adapt to working in the UK.