South African officials will inspect workplaces to see if firms are employing undocumented foreigners, the home affairs minister says.
Malusi Gigaba added that more than 60 employees of retail chain Spar “without documentation” had been arrested.
Mr Gigaba warned that firms would be “penalised” if they breached the law, and said they should not fuel tensions by “playing locals against foreigners”.
His comments come amid concern that xenophobia is rising in South Africa.
Many unemployed South Africans accuse foreigners of taking their jobs.
In the past week, Nigerian nationals have been attacked in the capital Pretoria; on Monday, 34 foreign-owned shops were looted in parts of Pretoria, and a local group has called for a march for Friday to protest at immigrants it says are taking their jobs.
The attacks triggered condemnation by the Nigerian government and a call by MPs for Nigeria’s ambassador to South Africa to be recalled.
But South Africa’s foreign affairs department dismissed claims that Nigerian nationals were targets of xenophobic violence.
Spokesperson Clayson Monyela said the attacks were nothing more than sporadic criminal incidents. The government also said inflammatory social media statements by South Africans and foreign nationals against each other were unnecessary.
However, Thursday saw protesters in the Nigerian capital, Abuja, target the head office of South African telecoms company MTN in apparent retaliation for violence against Nigerians in South Africa.
Mr Gigaba, whose comments have been published on the government’s Twitter account, said South Africans should not be portrayed as “mere xenophobes”.
He added that 33,339 people had been deported in 2015-16.
In his budget speech on Wednesday, South African Finance Minister Pravin Gordhan said that 35% of the labour force was unemployed or had given up looking for work.
South Africa experienced its worst outbreak of violence against foreigners in 2008, when more than 60 people died.
Two years ago, similar unrest in the cities of Johannesburg and Durban claimed seven lives as African immigrants were hunted down and attacked by gangs. BBC News