Authorities were monitoring a protest in Durban's Springfield Park on Monday, where hundreds of people gathered to demonstrate against the employment of undocumented migrants.
A group of approximately 300 protesters moved through the business district along Peter Road, reportedly going from one business to another and requesting worker documentation and employment records.
KZN VIP Security spokesperson Gareth Naidoo said the crowd had been questioning business owners about the legal status of their employees.
"This crowd is going door to door to different businesses, questioning and looking for employment details of staff who are working there," Naidoo said.
He added that while the protest remained peaceful, the number of participants appeared to be increasing.
Naidoo urged business owners to remain calm and avoid confronting the demonstrators.
"It is illegal for them to be going through and questioning businesses without the presence of the police. So, it's best they contact their service providers and ensure that their businesses are safe during this time to avoid any damage to infrastructure or any harm to their employees," he said.
Monday's protest comes less than a day after King Misuzulu kaZwelithini appealed for calm and warned South Africans against targeting foreign nationals amid growing tensions over illegal immigration.
Speaking during an International Yoga Day event in Durban on Sunday, the Zulu monarch said violence and hostility towards migrants were tarnishing South Africa's image across the continent.
"We live in difficult times where we are desperate for peace. We are angry, we are hungry for peace. South Africans, we are asking, we are not looking good to the whole of Africa right now," the King said.
His comments come as anti-illegal immigration civilian groups have set 30 June as a deadline for undocumented migrants to leave South Africa. The government has distanced itself from the ultimatum, stating that it has no legal standing.
King Misuzulu acknowledged that illegal immigration remains a serious concern but stressed that the issue should be addressed through lawful means and not through violence.
He warned that the unrest associated with some protests was damaging the country's reputation internationally and called on citizens to uphold peace and social cohesion.