Malawian Vice-President Joyce Banda took over in the southern African nation on Saturday after the death of President Bingu wa Mutharika, and fears of a succession struggle receded as top officials and the army backed the constitutional handover.

Banda, a 61-year-old women's rights activist and education campaigner, was due to be sworn in as president later on Saturday in the Chinese-built National Assembly in the capital Lilongwe, officials said.

She will become southern Africa's first female head of state.

The government only officially confirmed 78-year-old Mutharika's death earlier on Saturday, two days after he had died following a heart attack.

His body had been flown to a military hospital in South Africa.

The delay in the announcement had raised worries about a political crisis because Banda had been expelled from Mutharika's ruling DPP party in 2010 after an argument about the succession, though she retained her state position.

Dispelling fears of a power struggle, Banda appeared at a news conference in the capital Lilongwe to declare 10 days of official mourning for Mutharika, who had ruled for eight years. She ordered national flags to be flown at half-mast and the state broadcaster to play sombre music.

"I call upon all Malawians to remain calm and to keep the peace during this time of bereavement," Banda said, flanked by members of the cabinet, the attorney general and the heads of the army and the police.

"As you can see, the constitution prevails," she said, wearing a colourful black, silver and pink robe and headdress.-Reuters