Britain may still be recruiting nurses who are badly needed in the developing world, according to an international finance body.

A report by the Organisation for Economic Co-operation and Development warned the NHS recruitment code does not appear to be halting the problem.

Figures in a study released on Wednesday claimed rules put in place in 1999 to prevent recruiters taking nursing staff from developing countries had only produced a short-term "dip" in numbers.

The OECD found that after the code of practice was introduced the number of nurses recruited from South Africa by the UK fell by 374.

But a year later in 2001 the number of nurses leaving to work in the UK shot up by 45 per cent.

The problem is acute for South Africa - figures for 2001 revealed 17 per cent of all South African doctors and 5.4 per cent of nurses were working abroad.

"Trends in International Migration" concluded that although emigration is not the fundamental reason for the difficulties facing healthcare systems in developing countries, it does aggravate the problem.

But the report played down long-term implications.

"Although there is no question about the justification of this approach from the standpoint of fairness, its impact remains to be proved," said the OECD.

"It is probably too soon to evaluate precisely the impact of such a measure in practical terms, but several factors suggest that, in all events, it will be limited."

The report highlighted that although the code promotes good practice there were no sanctions for trusts or agencies found to have broken it.

Despite its concerns, the OECD praised the government for attempting to address a problem which few other governments had tried to solve.

"The first steps towards the definition of a code of practice for international recruitment of health workers represent a decisive move towards better regulation of the international market for health professionals," it said.

"Such a move is all the more necessary, given the imperfections of the market in question, and the nature of health as a global public good."