Congo's opposition plans to turn the sprawling capital Kinshasa and other cities across the country into ghost towns in a show of force after the country's highest court confirmed President Joseph Kabila as winner of a disputed November 28 election.

A spokesman for the opposition said on Saturday it will ask Kinshasa's 8 million residents to stay at home, joining people across the vast Central African nation in shutting down businesses and bringing public services to a standstill.

Democratic Republic of Congo's Supreme Court in a ruling on Friday, said Kabila won the November 28 election, rejecting opposition demands for the vote to be annulled over fraud allegations.

The court said the opposition had failed to prove the vote was rigged.

The Secretary General for opposition leader Etienne Tshisekedi's UDPS party said Congo's opposition parties will meet early next week, to issue to call.

On Monday there will be a massive meeting of all opposition parties in Kinshasa, and on Tuesday we are calling for 'ghost towns', said Jacquemain Shabani Lukoo.

Kabila is expected to be sworn into office on Tuesday December 20, according to Kikaya Bin Karubi, Congo's ambassador to Britain and a top official in Kabila's camp.

Several heads of state have already confirmed they are coming, Karubi said.

CRISIS RISK

Kinshasa, was calm on Saturday as people went about their businesses, while busloads of Kabila supporters shuttled around town, celebrating his victory.

Congo's second post-war vote was expected to set the mineral-rich nation, more than half the size of the European Union, on the path to recovery and spur further investments in its resources.

But the disputed election risks plunging it into a prolonged crisis.

Government spokesman Lambert Mende, said the opposition was free to protest as long as they do not disturb other people or break the law.

We are in a democratic country. If they want to demonstrate every day, they are free to do so but they must work with local authorities, Mende told Reuters by telephone on Saturday.

Observers said the vote, long hampered by organisational hurdles before it was held on November 28, was marred by violence and other irregularities and the results lacked credibility.

Two U.S. senators on the foreign relations subcommittee on African Affairs said in a statement it was troubling for the Supreme Court to declare Kabila as winner without a transparent review of the election results despite irregularities.

We are increasingly concerned that the election irregularities are a setback for already weak systems of governance in Congo, and may further destabilise the DRC and lead to an escalation of violence, Senators Chris Coons and Johnny Isakson said in a joint statement.

(Writing by Bate Felix; Editing by Sophie Hares)