National elections in Congo have been marred by delays and logistical problems, as well as fraud and violence. Opposition presidential candidates have rejected the extension, saying it violates the constitution.

Five Congolese opposition presidential candidates have called for a rerun of the general elections that were beset with voting delays.

They claimed the Election Commission's decision to extend the ballot into Thursday for some voters was "not constitutional."

Nearly a third of polling booths in the country had not opened and about 45% of voting machines suffered technical problems, observers said.

Polling stations that never opened on Wednesday would conduct voting on Thursday, the electoral commission said.

What we know about the delay

The impoverished but mineral-rich central African nation staged four concurrent elections on Wednesday -- to pick a president, national and regional lawmakers as well as local councilors.

Denis Kadima, chair of the electoral commission, said around 70% of voters had been able to vote on Wednesday and the delays would not affect the credibility of the process.

But in some cases, polls never opened, leaving people unable to cast ballots.

The decision by the National Election Commission to extend the vote -- and the problems on the first day of voting -- came at the end of a divisive campaign.

Previous election disputes have been known to lead to violence and pose a risk to the peaceful transfer of power.

President Felix Tshisekedi, 60, is running for a second term in office against a backdrop of years of economic growth but little job creation and massive inflation.

Around 44 million Congolese -- in a nation of 100 million -- are registered to vote. And more than 100,000 candidates are running for various positions.

Results are not expected for several days.

Congo is the third-largest global producer of copper and the top producer of cobalt, a battery component crucial to a global shift toward more sustainable energy sources.

mds/rc (Reuters/AFP)