Private agencies that supply the NHS with overseas medical staff are flouting the ban on targeting developing nations.

The nurse recruitment manager of a major London hospital told The Independent that agencies evaded the ban by instructing recruits to say they were applying of their own volition.

The code of practice banning active recruitment from Third World countries was introduced in 1999 in response to criticism that Britain was stripping poor nations of their skilled health workers. But the ban did not extend to individuals who had chosen to come to Britain to work, on human rights grounds.

The manager, who declined to be named, said: "Finding the nurses we need is impossible. All London hospitals have huge vacancy rates for nurses and rely on recruits from abroad."

"We have a website and we try to recruit from Australia, New Zealand and the US but we have to accept nurses from other countries as well."

Under the code, which is voluntary, the recruitment agencies are not allowed to advertise in the professional journals in the country where they are recruiting but can do so through their website.

"They will say to applicants - 'Don't say we were looking for you, say you were looking for us," said the manager.

More than 40 per cent of the 34,627 nurses who joined the UK register in 2003-04 were from overseas, including almost 3,000 from African countries which are on the banned list.

Tom Sandford, director of the Royal College of Nursing, England, said the code of practice was ineffective.

"The NHS can do back-door recruitment. Private agencies will recruit nurses for private hospitals, which remain outside the code, and once those nurses are in the UK they apply for NHS jobs."

"It is dishonest for the NHS to say it is not recruiting from these countries. What the Government could do is ensure everyone signs up to the code. John Hutton [former health minister] outlined changes to the code last August but they did not include the private sector."

A health department official said the UK was the only country in the world to have implemented a ban on active recruitment from developing countries and the NHS did not deal with private agencies that had failed to sign up to it.

Some private hospitals had also signed up to the code but there were no powers to compel them to do so, a spokeswoman said. "We can't make an independent care home sign up because they are not part of the NHS," she added.

The Royal College of Physicians said the NHS was failing to take advantage of the refugee doctors, estimated at more than 1,000, already present in the UK, rather than seeking new recruits from overseas.

A survey of more than 150 refugee doctors found 85 per cent did not have posts in the NHS. More than half were unemployed while others took jobs as labourers, chefs and security guards.

Professor Roger Williams, the international director of the college, said: "Refugee doctors are a resource that is not leaving the UK, they are here to stay to rebuild their lives and they need our support."

Sarah Hayward of the Employability Forum, which was set up five years ago to help refugees into work, said: "We should be looking at the skilled health workers we have already got in this country."