KINSHASA (Reuters) -- Democratic Republic of Congo's Supreme Court proclaimed Joseph Kabila president after throwing out a legal challenge to his election victory by rival Jean-Pierre Bemba.

"Mr Kabila Kabange, Joseph, is proclaimed president of the Democratic Republic of Congo, elected by absolute majority," the tribunal said in a statement read out in a temporary courtroom heavily guarded by Congolese police and UN peacekeepers.

Cheers from supporters of Kabila -- president since his father Laurent's assassination in 2001 -- greeted the announcement and cars outside honked their horns. In the Kabila stronghold of eastern Congo, people celebrated in the streets.

Some supporters in Kinshasa also rejoiced, but the city's normally bustling center was almost deserted apart from a large Congolese army and police presence. UN peacekeepers were on patrol, and shops had closed early before the court ruling.

"That's it, we've won, and it's now time for Bemba to go back to the jungle," said one man. The court rejected a challenge filed by former rebel warlord Bemba against results from the October 29 presidential run-off showing Kabila had won 58.05 percent of the votes against 41.95 percent for Bemba, whose camp had alleged "systematic cheating."

"The Supreme Court of Justice receives the request of the MLC (Bemba's party), but declares it unfounded," Supreme Court President Kalonda Kele said in a statement.

The court session, which confirmed the result already announced by electoral authorities, was held in the Foreign Ministry in Kinshasa, because the Supreme Court building was set on fire by rioting Bemba supporters last week.

The poll was the culmination of Congo's first free polls in more than four decades, aimed at ending years of and war, dictatorship and chaos in the vast former Belgian colony in central Africa.

Bemba's lawyers boycotted the court after it rejected their request to reopen the debate over the election result.

"This is a decision that will be taken without a real debate, so there is no point in our being there," Bemba spokesman Moise Musangana told Reuters before the announcement.

Afterwards Musangana declined comment, saying Bemba would make a statement in due course.

The court ruling had been anxiously awaited in Kinshasa, where Bemba's and Kabila's soldiers fought gun battles in the sprawling riverside capital earlier this month and in August.