Abuja (AFP) - Problems with new technology on Saturday forced voting to be extended in presidential elections in Africa's most populous nation, Nigeria, as renewed Boko Haram violence hit the knife-edge polls.
The Islamist militants were suspected of killing at least seven people in separate attacks in northeastern Gombe state, including at polling stations, while on Friday, 23 people were beheaded in Borno state.
President Goodluck Jonathan was the most high-profile victim of the glitches with handheld readers, which scan biometric identity cards to authenticate voters to help cut electoral fraud.
His main opponent, former military ruler Muhammadu Buhari, had no such problems and was accredited without a hitch in his hometown of Daura, in northern Katsina state.
Jonathan, who is seeking a second term of office, was forced to abandon his attempt to register electronically for the ballot in his home town of Otuoke, Bayelsa state, after the card reader repeatedly failed.
The 57-year-old was then accredited by hand and was able to cast his vote. He said afterwards: "As head of state, I don't blame anybody... I think the problem is national."
- 'Huge national embarrassment' -
The Independent National Electoral Commission (INEC) accepted there had been "challenges" with the technology in "many" places that had forced polling officials to suspend the process.
There was no immediate figure on how many people were affected, with voters also reporting the late and even non-arrival of election officials in some places.
The commission said voting would be extended into Sunday in 300 of the 150,000 polling stations due to the glitches.
During the election campaign, Jonathan's Peoples Democratic Party (PDP) repeatedly criticised the technology, which is designed to "read" fingerprints and other personal data in 10 seconds.
Buhari's main opposition All Progressives Congress (APC) backed the use of the devices as a way of combating widespread vote-rigging in previous elections.
PDP spokesman Olisa Metuh described the technological failure as "a huge national embarrassment" and a "vindication" of the party's position that it should not have been used without proper testing.
Three PDP governors were among those who also encountered difficulties, he added, calling for a "thorough explanation" from INEC.
- Polls attacked -
Boko Haram has dominated the election campaign, with the Islamist militant group's leader Abubakar Shekau having threatened to disrupt the vote.
A recent spate of suicide bombings and attacks on "soft" targets such as markets and bus stations raised fears about the safety of voters and led to stringent security measures countrywide.
The rebels, who have recently been pushed out of captured territory in the restive northeast by a four-nation military coalition, appeared to hold good to that pledge by attacking Gombe state.
At least seven people were killed when suspected Boko Haram gunmen launched separate attacks in the neighbouring villages of Birin Bolawa and Birin Fulani, the town of Dukku and nearby Tilen village.
In the first three attacks shots were fired at voters at polling stations and election materials were burned.
An election official, who requested anonymity, said: "We could hear the gunmen shouting, 'didn't we warn you about staying away from (the) election?'"
The beheadings happened in Buratai on the eve of voting, according to a nurse in Biu and lawmaker Mohammed Adamu, who represents the town around 200 kilometres (125 miles) from the Borno state capital, Maiduguri.
It was unclear whether the massacre was poll related.
Voters turned out in force in Maiduguri, which has been repeatedly hit in the insurgency that has left more than 13,000 dead and some 1.5 million homeless.
Civilian vigilantes swept voters, many of them women widowed by the violence or separated from their husbands, with hand-held metal detectors.
"I am ready to cast my vote at whatever cost," said Tandalami Balami, who fled the recently liberated town of Gwoza to a camp in Maiduguri.
- Tight race -
Jonathan, Buhari and 12 other candidates are contesting the presidential poll, while 2,537 hopefuls from 28 parties are vying for 469 seats in parliament.
The president's ruling party has been in power since Nigeria returned to civilian rule in 1999 but the result is far from clear this time, with the opposition in its strongest position ever.
The president's inability to tackle Boko Haram -- until recently -- has dominated his tenure and while Nigeria became Africa's largest economy on his watch, global oil shocks have hit the country hard.
Even Jonathan has admitted that the election is close, with 72-year-old Buhari seen by some as an antidote to endemic government corruption and insecurity.
The tight race has prompted fears of a repeat of poll-related violence in which around 1,000 people were killed in 2011. There were sporadic reports of clashes on Saturday.
The technical stumbles could not have come at a worse time for Nigeria, after it delayed the scheduled February 14 vote by six weeks on security grounds.
INEC has said that results will be announced within 48 hours of polls closing.