Polling stations opened in some areas Saturday for Nigerian parliamentary elections, the first of three landmark ballots this month, but others were still shut an hour after the start time.
Voters on Saturday will select who should take seats in the country's National Assembly. The positions are worth more than $1 million in salaries and perks a year, not counting the power to influence the billions of dollars in oil revenues the country earns annually.
Polling places were due to open at 8:00 am (0700 GMT), with the first four hours set aside for the "accreditation" of voters -- an exercise aimed at verifying that their numbers match the number of ballots cast.
A number of polling places opened in the northern city of Kano, but voting stations in other areas, including the economic capital Lagos, were yet to begin activities due to the late arrival of material and personnel.
The election period will serve as a test of whether Africa's most populous nation can hold a credible ballot after a series of flawed and violent polls.
Ahead of Saturday's parliamentary vote, suspected Islamists have attacked a police station in northern Nigeria with explosives police said, but it was unclear if there were casualties.
"A number of gunmen suspected to be members of Boko Haram attacked Dutsen Tanshi police station," police spokesman Mohammed Barau told AFP of the attack in the city of Bauchi, referring to an Islamist sect that launched a 2009 uprising. "They threw explosives into the police station which detonated and fired several shots before fleeing."
The attack occurred on Friday night, on the eve of parliamentary elections, the first in a series of landmark polls this month.
Sect members attacked the same police station in 2009 as they launched an uprising that was later put down by a brutal military assault which left hundreds dead.
The sect has been blamed for dozens of killings and attacks in recent months.
The amount of damage to the station was also unclear as the area had been cordoned off. Residents reported by phone that soldiers in vans were being deployed in the area.
The sect has claimed to be fighting for the creation of an Islamic state in Nigeria, a country of some 150 million people divided roughly in half between Christians and Muslims.
It was believed to have been routed after the assault in 2009, but it re-emerged last year with a series of shootings by gunmen on motorbikes, as well as attacks on police stations and a prison raid that freed hundreds of inmates.
Most of the recent attacks have occurred in the northeastern city of Maiduguri, where the sect's mosque and headquarters were located before being destroyed in the 2009 assault.
It was blamed for three church attacks on Christmas Eve that claimed six lives and left one of the churches burnt down.
The sect has been known by various names. Boko Haram means "Western education is sin" in the regional Hausa language.