South African President Thabo Mbeki says his country has been disgraced by two weeks of anti-foreigner violence that has killed at least 50 people.

In a nationally-televised speech Sunday, Mr. Mbeki said South Africa has never seen such callousness since the end of apartheid. He said people must recognize the violence as an "absolute disgrace."

Mr. Mbeki said authorities would do everything possible to bring the perpetrators to justice.

Police have arrested hundreds of people since the violence began on May 11 with the killing of two immigrants in Johannesburg's Alexandra township.

Attackers have blamed immigrants for taking jobs and increasing South Africa's already-high crime rate. The country is home to an estimated five million immigrants. About three million of them are from neighboring Zimbabwe.

The head of the ruling African National Congress, Jacob Zuma, was met with hostility when he spoke to a crowd east of Johannesburg Sunday.

One heckler demanded Zuma tell other African leaders to keep their people home. The heckler threatened to wreck Zuma's presidential hopes next year if he takes no action.

The army deployed troops to parts of Johannesburg on Thursday to help control the unrest. Critics have accused the government of responding slowly to the crisis and not relieving the poverty widely considered the root of the bloodshed.

Some information for this report was provided by AFP and Reuters.