A demonstration against undocumented migrants in South Africa turned violent Thursday, with police arresting one foreign national and a community leader saying five Congolese migrants were injured.

The protest took place in the port city of Durban, which has become the epicenter of weeks of unrest over irregular migration. At least four foreign nationals have been killed and tens of thousands have fled the country amid the unrest.

Police said about 100 people affiliated with an anti-illegal migration group took part in what they described as a "clean-up campaign” targeting an encampment of several hundred foreign nationals outside a government office.

Many of those sheltering at the site are from the Democratic Republic of Congo. They moved there 13 weeks ago seeking protection from mobs of South Africans protesting the presence of undocumented migrants.

"During the commotion, stones were thrown around, and one which was thrown by a foreign national landed on a police officer,” police said.

The person was arrested, according to a police statement, which did not provide further details.

A leader of the group of foreigners told Agence France-Presse (AFP) that five Congolese nationals, including two children, were injured in the clash.

"The march today was very violent,” said Bishop Raphael, who is from the DRC.

"They found us here and immediately attacked our people. We are not committing any crime by being here. This is uncalled for,” he said.

Many of the people in the group claim to be refugees from the DRC.

Raphael said the protesters were armed with sticks and attempted to attack the encampment while police tried to separate the two groups.

Police used stun grenades to disperse the crowds, resulting in the injuries, he said.

Tensions have soared across South Africa after fringe groups campaigning against undocumented migrants set a June 30 deadline for them to leave.

More than 200,000 people have fled, according to an AFP tally based on figures released by African governments that have repatriated their nationals.

At least four migrants were killed in the violence, according to South African police, though some foreign governments say the toll is higher.