JOHANNESBURG, April 21 -- Calm was restored on Tuesday in Durban, Johannesburg and other areas hit by recent xenophobic violence that has lasted for several weeks, South African authorities have said.

No reports about looting of foreign-owned shops or clash between locals and foreigners have been received in Johannesburg since Monday, a police source said.

In Durban, normalcy has also returned to its affected areas, local authorities said.

In both cities, some shops opened on Tuesday but under heavy police security.

Durban and Johannesburg were the hardest-hit cities in the latest outbreak of attacks against migrants, mostly those from other African countries.

Authorities said the call by Zulu King Goodwill Zwelithini to end the violence played a role in restoring peace and stability.

The king addressed thousands at a rally in Durban on Monday.

Seven people - three South Africans and four foreign nationals - have been killed and thousands of foreigners displaced in the violence.

President Jacob Zuma has visited riot-hit areas and delivered speeches to appeal for calm.