The government is creating an ethical recruitment code to prevent authorities and agencies hiring social workers from developing countries.
The code, which is being produced by the Improvement and Development Agency and supported by the Department of Health, is intended to stop unethical recruitment practices.
Almost 4,900 overseas social workers registered to work in England from April 2004 to April 2006, Personnel Today's sister publication Community Care reports.
More than 900 applicants came from South Africa, followed by Australia, the US and India.
Ian Wilson, social services director at Tower Hamlets Council in east London, said UK councils should not be recruiting from developing countries, such as South Africa and Zimbabwe, where there were already severe skills shortages.
A Department of Health spokesman said the code was "still at its early stages" but that there was clearly an increase in the number of overseas recruits working in social care in the UK.