The UK is playing a pivotal role in stripping English-speaking sub-Saharan Africa of its doctors and nurses, says a report published today.

The Department of Health forbids the NHS from recruiting from countries struggling to treat sicker populations. The code of practice does not cover private hospitals and agencies, although the health minister John Hutton said last August it would be tightened.

But, John Eastwood, from St George's hospital school of medicine in Tooting, south London, and colleagues say in a report in the Lancet: "It is difficult to believe that strengthening the code on its own will overcome the demand. It is this demand that appears to be the principal cause of the drain."

Overseas staff make up a large proportion of the medical workforce - 31% of practising doctors and 13% of nurses were born outside the UK, they say. Nearly half of the recent 16,000 expansion of the NHS workforce came from outside the UK and Europe. Although some other countries lack doctors, "the problem is especially severe in sub-Saharan Africa", they write. An estimated 60% of doctors who in the 1980s trained in Ghana - which has only nine doctors per 100,000 population and is being overwhelmed by the HIV/Aids epidemic - have left.

In 2003, say the authors, work permits were approved for 5,880 personnel from South Africa, 2,825 from Zimbabwe, 1,510 from Nigeria and 850 from Ghana - even though they are all on the list the NHS is not allowed to recruit from.

There has been a "medical carousel" with doctors from Tanzania, Kenya and Nigeria moving to the UK, British doctors moving to Canada, and Canadian doctors migrating to the US. But, says Dr Eastwood, nobody goes to fill the empty posts in Africa.

The authors propose other measures, such as helping poor countries retain doctors with housing and transport incentives. The Home Office could also restrict work permits so that those who train in the UK go back afterwards.