An electoral commission agent seals a ballot box in front of observers in Lubumbashi's Mapala district on December 30.
Goma, Congo CNN  — 

An opposition leader in the Democratic Republic of Congo has complained of voting irregularities following Sunday’s long-awaited presidential elections.

Martin Fayulu, a former oil executive and one of three frontrunners, claimed Monday that electronic voting machines malfunctioned at some polling stations, triggering widespread delays to his supporters.

“In many centers across the country, voting machines did not work … Voting operations were interrupted following the malfunction of voting machines,” Fayulu told reporters.

The opposition coalition has often objected to the use of voting machines, arguing they could facilitate vote rigging.

Despite the setback, Fayulu hailed Sunday’s elections – originally scheduled to be held in 2016 – as Congo’s departure from the “power of Kabila,” while his coalition expressed confidence in securing victory.

Sunday’s vote is meant to pick a successor to Joseph Kabila, who has held the presidency since 2001, and could mark the country’s first-ever democratic transfer of power.

Twenty-one candidates including Kabila’s former interior minister, Emmanuel Ramazani Shadary, entered the presidential race. Of the opposition candidates, only two are considered to have a serious chance of beating Shadary: Fayulu and Felix Tshisekedi, leader of the largest opposition party.

In Goma city, polling stations opened several hours late and closed later than scheduled. Voters told CNN they had queued for hours to cast their ballots but were forced to wait until late evening because some of the voting machines had broken down.

Improvised electoral agents count ballots after a symbolic vote on December 30, 2018, at Kalinda Stadium in Beni, where voting in the general election was postponed.

Electoral officers have already begun collating results, and provisional results have been posted in some polling booths. The election uses a first-past-the-post system to declare a winner.

However, the electoral commission’s controversial decision to delay voting in three opposition strongholds has all but guaranteed the result will be challenged.

On Wednesday, the independent voting body said the ballot in the cities of Beni, Butembo and Yumbi would be delayed until March, citing an Ebola outbreak and potential militia violence, sparking protests from furious would-be voters.

The decision technically canceled more than a million Congolese votes from the opposition strongholds as the final election result is expected to be announced in mid-January.

Voters in Beni staged a mock vote on Sunday to protest the electoral commission’s decision, lining up at makeshift polling stations and pressing their fingers on papers.

Journalist Patrick Felix Abely reported from Goma in the eastern Democratic Republic of the Congo while CNN’s Bukola Adebayo wrote from Lagos, Nigeria.