Dozens of people have been arrested in the South African city of Johannesburg after rioters looted shops and torched buildings and vehicles.
Police fired tear gas, rubber bullets and stun grenades in an attempt to quell the unrest on Monday.
Many of the targeted shops are reported to be owned by foreign nationals.
But the country’s police minister, Bheki Cele, said “criminality rather than xenophobia” was to blame for the “senseless violence”.
“Xenophobia is used as an excuse,” he told reporters after visiting the city’s Central Business District, where much of the unrest has been taking place. “Nothing… has sparked any form of conflict between the South Africans and foreign nationals.”
However, Nigerian Foreign Minister Geoffrey Onyeama said Nigerian shops had been targeted by “mindless criminals” and promised to take “definitive measures”.
South Africa has seen a spate of xenophobic attacks in recent months. In March, three people died during protests that targeted foreign-owned shops in Durban.