Election officials in the Democratic Republic of Congo say they will announce the complete results of a presidential poll on Thursday, as the nation braces for possible civil unrest.

After postponing the announcement by two days because of logistical problems, election commission spokesman Matthieu Mpita said the full results will be released after 6 p.m. local time .

Preliminary results from nearly 90 percent of polling places showed incumbent President Joseph Kabila headed for re-election with almost 50 percent of the vote. His closest challenger, Etienne Tshisekedi had 33 percent.

The capital, Kinshasa, has been largely calm, but supporters of both men have hinted that violence could break out if their candidate is not named the winner.

Troops are on standby in case of unrest, and the United Nations, European Union and African Union have urged calm.

The independent International Crisis Group on Thursday called on the international community to mediate the crisis in order to avoid bloodshed.

The balloting was only the second free election since the African nation was torn apart by several years of warfare that ended in 2003.

Voting was supposed to last for one day but stretched into three because of ballot shortages and scattered incidents of violence.

The delay in releasing results means Mr. Kabila has remained in office past the end of his term, which expired at midnight Tuesday.

Human Rights Watch reports violence leading up to the vote killed least 18 people.