South African police said Thursday they had rescued 44 Ethiopian nationals, 17 of them minors, who were being held against their will in an upscale neighbourhood of Johannesburg.

The incident is the latest in a string of human-trafficking cases in Africa's most industrialised nation, a magnet for undocumented migrants from across the continent.

Officers on patrol were alerted to the discovery by screams coming from the house in Sandton, spokesman Lieutenant Colonel Mavela Masondo told journalists.

"We found that there were 44 illegal immigrants that were locked in rooms," he told Newzroom Afrika television.

Minors rescued

Seventeen of them were minors, he added.

"We are still waiting for an interpreter that will help us get more information from them," Masondo said.

In March, dozens of young Ethiopian adults and children who were also allegedly held captive in a suburban house in Johannesburg escaped, with police finding 32.

It was not immediately clear if the two cases were connected.

Found naked

In January, police rescued 26 undocumented Ethiopians found naked and without documents in Johannesburg, held by suspected traffickers.

Last August, more than 80 were discovered locked in a house in inhumane conditions in another suburb of the city.