The RCN says nurses are coming to the UK from countries 'who can least afford to lose them'

The government is expected to set out a voluntary code to crack down on the practice later in the week.

There is an existing ban - but it only covers NHS recruitment of permanent staff from these countries.

The Royal College of Nursing welcomes moves to close loopholes but says the new rules should be mandatory.

We would like to see something that had some teeth to it Beverley Malone, Royal College of Nursing

Nursing staff from Africa are coming to work in the UK because pay is so much higher here than at home.

More than 1,300 nurses arrived in Britain last year from South Africa, with another 500 coming from Nigeria.

Many are hired by private hospitals. They can then be recruited by agencies looking for staff ready to transfer to the NHS.

'Not just encouragement'

The new measures are expected to ask private hospitals to sign up to the NHS code, covering 150 poor countries.

In return they will be offered access to the government's international recruitment programme.

The Royal College of Nursing says it welcomes any extension of the code, but says it fears it will not be strong enough.

Beverley Malone, RCN General Secretary, told BBC Radio 4's Today programme: "We would like to see something that had some teeth to it.

"We would like to see the government implement something that does not just encourage, but says something must be done."

Ms Malone said she would like the government to use inspectorates such as the Healthcare Commission to ensure the code was implemented.

"It's been a back-door for the NHS to end up having nurses from those countries who can least afford to have nurses come, some of them African countries which are plagued by Aids."