"This is a classic refugee situation," Rachel Cohen from Doctors Without Borders told the BBC. "I have treated bullet wounds, beaten people, rape victims and the people are terrified."

Zimbabweans, estimated to total 3 million, make up most of the immigrant population, aid workers said.

Immigrants have become a target for South Africans angry over a rise unemployment and crime and a lack of housing, the BBC said. Assaults began a week ago in Alexandra township, spreading to Johannesburg and the Gauteng region.

An attack on the Central Methodist Church in Johannesburg where about 1,000 Zimbabweans are housed prompted Bishop Paul Veryn to urge a state of emergency be declared.

South African President Thabo Mbeki said he would set up a panel to investigate the violence.

Jacob Zuma, head of the African National Congress, condemned the attacks.

"We cannot allow South Africa to be famous for xenophobia," he said.