JOHANNESBURG -- South Africa will deploy the army to areas that remain volatile after a spate of violent attacks targeting immigrants, the defence minister announced on Tuesday.

Soldiers will be sent to support police in troubled areas, Defence Minister Nosiviwe Mapisa-Nqakula said in a live broadcast.

The minister made the announcement in Alexandra, a Johannesburg township where a Zimbabwean couple survived a shooting overnight. Both Zimbabweans were treated and discharged from hospital.

In the same Alexandra area, a Mozambican man was stabbed to death by four South African men over the weekend. Four South African suspects appeared in court on Tuesday and remain in jail, said Velekhaya Mgobhozi, the National Prosecuting Authority spokesman.

Troops will also be sent to Durban, the coastal city where the attacks on foreigners began, Mapisa-Nqakula said. The violence has been concentrated in areas of Johannesburg and Durban where poor immigrants and South Africans live.

By nightfall Tuesday, no troops were seen in Alexandra in Johannesburg.

The violence has forced nearly 7,000 immigrants into camps around Durban, Doctors Without Borders said in a statement. Camps have also been set up in Johannesburg. The recent spate of attacks has mainly affected immigrants from African states like Malawi, Mozambique and Zimbabwe, said the statement.

In Malawi, nearly 2,000 protesters marched to the South African High Commission, demonstrating against the wave of violence, said Billy Mayaya, a human rights activist.

"South Africa, why kill your fellow blacks?" read one poster carried by the singing demonstrators in the capital Lilongwe. The march organizers called on the South African government to do more to protect immigrants.

Nearly 400 Malawians returned home on Monday, travelling overnight by bus from South Africa, Malawi's Information Minister Kondwani Nankhumwa said.

In neighbouring Mozambique, more than 100 Mozambicans have returned from South Africa, the Mozambican Ambassador to South Africa, Fernando Fazenda, said.

Mozambican President Filipe Nyusi asked Mozambicans not to retaliate by attacking South Africans living in the country or South African businesses operating there.

Associated Press writers Raphael Tenthani in Lilongwe, Malawi, and Emmanuel Camillo in Maputo, Mozambique, contributed to this report.