Democratic Republic of Congo President Joseph Kabila has won re-election, said the head of the electoral commission Friday, urging calm after a provisional result that the opposition called totally unacceptable.

Streets had emptied before the result in parts of the capital Kinshasa and police in riot gear were deployed in case of clashes.

The electoral commission notes that the candidate Joseph Kabila has achieved a majority with, 8,880,944 votes, or 48.97 percent of votes cast, Daniel Ngoy Mulunda told reporters, officials and diplomats gathered to hear the poll's outcome.

(The results) are no reason to whip up the population against the established order to contest the results, or to settle scores, said Mulunda.

He said challenger Etienne Tshisekedi was runner-up with just over 32 percent.

Tshisekedi's campaign president Alexis Mutanda told Reuters: It is a totally unacceptable result. You can just look around Kinshasa or the rest of the country to see how many people are against these results. The population is totally disoriented.

He said Tshisekedi's UDPS party had not decided on its next move, but had no faith in the credibility of the Supreme Court charged with ratifying the results.

At least 18 people have been killed in election-related violence so far, according to U.S.-based Human Rights Watch.

The opposition has accused Kabila's government of vote-rigging, and his camp has warned that the government would call in the army if protests became too chaotic.

The November 28 poll was Congo's first locally organised presidential vote since a war that killed more than 5 million, and is meant to move the country toward stability and encourage foreign investment after years of conflict and turmoil.

The announcement of the result had been delayed twice earlier in the week due to logistical problems and as donor nations urged more transparency, stretching the nerves of residents eager for an outcome.

International observers have said the election process has been marred by irregularities and disorganisation, but have stopped short of calling for it to be annulled.

Before the results were announced, convoys of police trucks patrolled the city, security forces carrying tear gas launchers were deployed on street corners, and shops shut early.

The government of neighboring Congo Republic said this week it is preparing a refugee camp north of Brazzaville in case violence forces people to flee across the Congo River.

(Additional reporting by Emmanuel Braun; Writing by Richard Valdmanis; Editing by David Lewis and Rosalind Russell)