Voting in Nigeria's hugely significant presidential election will continue into Sunday following a spate of technical issues that kept people waiting for hours.

Notorious militant group Boko Haram also launched two attacks on in the country's north-east, with gunmen opening fire on voters in Yobe and Gombe states — killing six people.

And there were two car bombs that did not kill anyone, and another two that were safely detonated by police.

Tens of millions of Nigerians today turned out for the closest political contest the country has ever seen.

Despite late-arriving ballots, the technical accreditation issues, and the attacks from violent insurgents, reports from the ground indicate there has largely been a feel-good atmosphere around polling stations.

President Goodluck Jonathan, who faces a legitimate challenge from former military dictator Muhammadu Buhari, spent nearly an hour waiting for approval to vote, according to the BBC.

After voting, Jonathan stressed patience in an interview with Channels TV: "I appeal to all Nigerians to be patient no matter the pains it takes as long as if, as a nation, we can conduct free and fair elections that the whole world will accept."

The biometric cards, which scan fingerprints, were designed to deliver assurances as to the legitimacy of the vote, with previous elections marred by accusations of election-fixing.

Officials had earlier said everyone will give every a chance to vote, even if it takes all night, but this evening chose to extend voting times till the following day.

Nearly 60 million people are registered to vote.

Roads across the country are closed except to election officials, who have delivered voting materials via everything from speedboats to camels, according to the Independent National Electoral Commission.

Using the hashtag #NigeriaDecides2015, voters have flagged delays in the process with election officials arriving hours late to more rural areas.

After the 2011 election, in which Jonathan defeated Buhari by a significant margin, there were violence riots during which around 1,000 people died. There is concern that something similar could happen this time, despite both leaders signing a peace agreement on Thursday.

Reuters reports that a group calling itself the Nigerian Cyber army have hacked into the electoral commission's website, issuing a warning against rigging the election.

The message read: "If you attempt to rig, you will pay."

Boko Haram, the mass-murdering Islamist group that has made considerable gains in the country's north, is the big issue of this election.

This is only the eighth election since Nigeria's independence from Britain in 1960. UN Secretary General Ban Ki-moon said: "The international community has high expectations that Nigeria will provide leadership in setting a high standard for this election."