Police said that mobs attacked Somalis and Zimbabweans in Cape Town on Friday, looting their homes and shops.
Hundreds of African migrants were moved from a squatter camp near the city, while Somali-owned shops were also looted in Knysna, a resort town on the southwestern coast.
Al Jazeera's Yvonne Ndege, reporting from South Africa, said immigrants were being chased from their homes.
"At least 100 - but some are saying it's more - Somalis and Zimbabweans have been evicted from informal settlements," she said.
She also reported that there had been attacks against Somali businesses due to "a perception in South Africa that Somalis come in and do well in business".
"Some of the businesses [that have been] looted and emptied of their goods essentially belonged to the Somali community," she said.
In Durban, on the east coast of South Africa, one man was shot dead and in Mumpalanga northwest province three foreigners were attacked on Thursday.
"The army did come out to support security operations mounted by the the South African police if things got out of hand," said Ndege.
"The authorities and police and army are poised to act if there are any more incidents of violence."
Billy Jones, senior superintendent with the Western Cape provincial police, said: "We don't know the exact number of shops looted and burnt, but it's a lot."
He added that one Somali died overnight but it was unclear whether the death was linked to the attacks.
At least 42 people have been killed and more than 25,000 driven from their homes since unrest broke out 12 days ago.
The migrants are accused of taking jobs from South Africans and fuelling crime.
A group of black South Africans involved in the violence told Ndege in Johannesburg that foreigners were undoing years of fighting against white rule and undermining the minimum wage.
Police are patrolling the streets and the army has been called in to contain an outbreak of violence.
Sfiso Nkosi, a 26-year-old local in Primrose, Johannesburg, took part in the violence and, like others, shared in the spoils of the unrest - property looted from foreigners.
He said he had no choice but to join in the violence as there was peer pressure to do so.
|Mozambique expects many more of its citizens|
to return, following the violence [AFP]
Other locals expressed anger, arguing that Africans from neighbouring countries were prepared to work for only $4 a day when they insist on a minimum of wage of at least $12.