Authorities in the Democratic Republic of Congo have banned a so-called “swearing-in” ceremony for opposition leader Etienne Tshisekedi, who insists he won last month's election.

Security was heavy around the Kinshasa stadium where Mr. Tshisekedi had scheduled the ceremony Friday.

Earlier, a Tshisekedi adviser told VOA that the ceremony would proceed, despite a government threat to arrest the opposition leader.

The country's electoral commission named incument leader Joseph Kabila the winner of last month's presidential election but Mr. Tshisekedi, who finished second, rejected the result and proclaimed himself president.

His adviser Valentin Mubake says Mr. Kabila won only through “massive fraud” and rejects assertions that Mr. Tshisekedi might destabilize the country.

“Before thinking about the destabilization of the country, we have to think about the truth of the vote. The reality of the elections is that Mr. Tshisekedi has been elected by the Congolese people. That (means) the stabilization of Congo and that is reality.”

International observers said the poll was deeply flawed, especially in the vote-counting process that American observers termed chaotic.

The election has sparked protests both inside and outside the DRC. On Thursday, rights group Human Rights Watch said Congolese security forces have killed at least 24 people since Mr. Kabila's victory was announced last week.

The report said security forces have been firing on small crowds in an apparent attempt to prevent demonstrations.

The November presidential and legislative polls were only the second free elections in the Democratic Republic of Congo's history.

Vote counting in the parliamentary elections was suspended this week. Officials say they need assistance from foreign election experts.