Issa Diallo told the BBC that a radio message was sent from the plane on Sunday after it came down near the central town of Huambo.

He renewed his call for Unita and the Angolan Government to observe a ceasefire to help the search for survivors.

The Angolan Government has accused Unita of shooting down the plane, but Unita has said it knows nothing about the incident.

It is reported that eight of those on the plane were members of the UN observer mission in Angola.

The UN observer mission said the plane burst into flames after taking off from Huambo, which has been the target of Unita shelling in recent weeks.

Aid flights suspended

The United Nations World Food Programme suspended aid flights in Angola after the crash.

A WFP spokesman said the food delivery flights were being called off until Wednesday as a precautionary measure until more was known about the crash.

The WFP flights are a lifeline for thousands of refugees who have fled to the provincial capital of Huambo, to escape weeks of heavy fighting in central Angola.