ANTANANARIVO -- Madagascan businessman Marc Ravalomanana was sworn in as president on Monday a week after a court declared him winner of disputed December elections, despite veteran ruler Didier Ratsiraka's refusal to step down.

"I solemnly take an oath before God, the nation and the people that I will assume the functions of president of the republic following the constitution and the laws of the state for the good of all inhabitants," Ravalomanana said.

It was the second time Ravalomanana, a self-made millionaire and mayor of Antananarivo, has been invested as ruler.

He declared himself president on February 22 at a ceremony in the capital, saying Ratsiraka rigged December 16 polls to ensure he would retain power, Reuters reported.

Ravalomanana, 52, has not officially been recognized as president by the international community, but representatives of foreign diplomatic missions were present at Monday's ceremony, among them four senior U.S. representatives.

Madagascar was thrown into chaos by the disputed December 16 poll. After months of crisis, with both men claiming to be president, the rivals agreed to a recount that showed Ravalomanana won 51.46 percent.

But Ratsiraka, 65, who has ruled the island of 16 million off Africa's southeast coast for more than 20 years, rejected the recount result, saying it was biased. The court announced its ruling on April 29.

Governors loyal to Ratsiraka have said they would secede from central rule if Ravalomanana took power, though it was not clear whether they had enough popular support to carry out their threat on the island larger than France.

Ravalomanana, who has already installed his government in the capital's ministries, was given military honors at the investiture ceremony. As president, he would also be in charge of the armed forces.

Ratsiraka has moved his Cabinet to the eastern port of Toamasina, his home region and political stronghold.

His supporters have erected barricades and blown up bridges on main roads to isolate the capital, cutting off supplies of fuel and other essential goods.

Health officials say as many as 60 people may have been killed in clashes between the two sides since the crisis began, and have warned of more violence if neither side concedes defeat.

Ratsiraka and Ravalomanana agreed to the recount at talks in Dakar last month, but Ratsiraka later said the court was biased and acting outside the bounds of the constitution.

The former socialist admiral also reneged on an agreement struck at the Dakar talks to remove the barricades surrounding Antananarivo.