WINDHOEK (AFP) - Experts carried out DNA tests on Monday to identify the 33 people who were on a Mozambique Airlines plane that crashed in Namibia killing all on board, an official said.

Thirty one bodies had by late Sunday been pulled from the charred wreckage of the plane in the swamps of northern Namibia's Bwabwata National Park.

"We are still busy," said Paul Ludik, director of the Namibia's national forensic science institute, adding "it will be difficult to say what time we are going to finish, considering the ... processes involved."

The institute is leading the probe into the crash and the processes to identify the victims.

"Namibia, as the country where the accident occurred, will lead the investigation," the airline said in a statement. Other investigators will be drawn from Angola, Brazil Mozambique and the US National Transport Safety Board.

The crash was one of the worst incidents in Mozambique's civil aviation history.

The passenger craft came down in torrential rains on Friday in the remote Namibian region killing its six crew and 27 passengers.

The victims' bodies were transferred by helicopter to the Namibian capital Windhoek from the crash site some 1,000km to the northeast.

The plane, which went down en route from Mozambique to Angola, was a Brazil-manufactured Embraer 190 aircraft and the newest plane in the airline's fleet.

The plane's black boxes have also been recovered along with two voice recorders, Captain Ericksson Nengola, director of aircraft accident investigations at the Namibian transport ministry said on Sunday.

Mozambique was to declare a national period of mourning for the victims, who came from Mozambique, Angola, Brazil, China, France and Portugal.

"We have also begun making arrangements for a memorial service for the families, loved ones, friends and colleagues of everyone who was on board," the airline said.