One person was killed at a mosque near Durban in South Africa when three men armed with guns and knives slit the throats of three worshippers, an emergency service official said on Thursday.

Africa's most industrialized country has a large expatriate community and attracts many tourists but has seldom been associated with Islamist militancy.

"One of the three has just died on his way to hospital. The other two are in critical condition," said Prem Balram, a spokesman for Reaction Unit SA, a private emergency service, who was among the first on the scene.

The motive of the attack was not clear but the three suspects, who fled in a white car, had been identified as Egyptian, he added.

"The suspects were Egyptian males. The local people here identified them," Balram said.

A section of the mosque was set ablaze and smoke was billowing from the side of the building, Balram said. One of the attack victims jumped from a side window of the smoking building.

Police were unavailable to comment.