A 16-year-old Lesotho pupil has died after his face was sliced off by a street sign while on a school tour in the South African city of Durban.

The boy had been looking out of the bus window as it drove down a narrow street in the city centre, witnesses say.

Police cordoned off the scene and covered the body with a blanket before it was removed by a mortuary van.

The teenager, whose identity has not been released, was among a group of 106 pupils from Molapo High School.

The authorities are investigating the circumstances around the teenager's death.

The students and teachers, who are said to be severely traumatised, are receiving counselling.

A security guard, who asked not to be identified, had been stationed outside a car dealership nearby.

"[The bus] first hit this sign; everybody was still inside... The boy then peeked his head out the window - he was sitting near the back - to see what was happening and before he knew it, he was struck by the sign on the second pole," he told the Durban Mercury.

"Everyone was crying, the teachers, the pupils; it was hectic. I wanted to help, but I couldn't. He was still breathing - blood still gushing - when I got to him. But there was absolutely nothing I could do for him," said another witness.