Tear gas has been fired in Democratic Republic of Congo at protesters angry that several opposition strongholds have been left out of Sunday’s polls.
Electoral officials have postponed voting in three cities until March, citing insecurity and Ebola concerns.
But with the new president due to be sworn in next month, it appears the votes of more than a million people will be discounted.
The opposition accuses the authorities of seeking to rig the ballot.
DR Congo has not had a peaceful and democratic transfer of power since independence from Belgium in 1960.
President Joseph Kabila, who has been in office since 2001, was meant to have stepped down in 2016.
However, the election to choose his successor has been continually postponed, amid unrest and logistical difficulties in a nation with poor infrastructure.
Opposition supporters suspect Mr Kabila is trying to cling on to power.
He denies the allegation and is backing former Interior Minister Emmanuel Ramazani Shadary in the election.
