"The details are sketchy but it is believed the chopper crashed in an open field. The policemen are burnt beyond recognition," said Zweli Mnisi, the spokesman for the police minister Nathi Mthethwa.

Mnisi could not disclose the identities of the deceased, nor the destination of the helicopter.

Paramedics were searching fields adjacent the crash site in Witbank, in the country's northern province of Mpumalanga, for the remains of three of the seven occupants.

South Africa's police have been celebrated at home in recent weeks for their work in preventing any major incidents at the soccer World Cup, which ended earlier this month.