Boys in their teens and a few scantily dressed girls, some who don't even look 14, emerge from the shadows.

One of the boys approaches the vehicle, bends towards the window and observes the occupants.

Three years ago, when he was 10 years old, Wairipi ran away from home in Okakarara, about 200 km north of Windhoek.

He is now 13 and sells sex on the streets of the capital, living under bridges with two of his friends. "When I first came to Windhoek I just wandered around with my friends begging during the day," he said.

It's on a hot, humid Saturday night in the seedy suburb of Ausspannplatz, south of the central business district of Windhoek, the Namibian capital.

The streets appear deserted, but this changes when a vehicle appears.

The smell of cheap wine and cigarettes floats around him.