A series of explosions in the Nigerian city of Kano on Friday included a suicide attack on a regional police headquarters that killed two officers, a police source said.

"There was a suicide attack on the police zone 1 headquarters," the senior police source said on condition of anonymity. "So far two officers have been killed and the bomber also."

An unidentified gunman has shot dead three Chadian nationals in the northeastern Nigerian city of Damaturu, hard hit by violence blamed on Islamist group Boko Haram, police said Tuesday.

The gunman armed with a rifle stole mobile phones from the Chadian masons and shot them dead on Monday in the Pompomari area of the city, a neighborhood torn in recent weeks by Islamist attacks and a military crackdown.

Nigerian President Goodluck Jonathan announced Monday a cut in petrol prices in a bid to end a nationwide strike now in its second week, as soldiers seized the main protest site in Lagos.

Jonathan made the announcement in a televised national address after a week that saw him remain largely silent in public as the strike and mass protests shut down Africa's most populous nation and largest oil producer.

Gunmen have attacked two pubs in northeastern Nigeria, killing four people amid a wave of such violence blamed on Islamist group Boko Haram, residents and police said Saturday.

The attacks occurred in two neighboring states on Friday night and involved gunmen riding on motorcycles storming in on the drinking spots.

A mob killed two people and burnt mosques and homes in an overnight raid on a mainly Muslim village in northeastern Nigeria in the latest such violence to hit the country, residents said Friday.

"It was around 11:30 pm (22:30 GMT) when a crowd from Imbur attacked Gwalam village, setting fire on homes and mosques," resident Abubakar Hussaini said, with Imbur a largely Christian area and Gwalam mainly Muslim.

Members of Nigeria's Islamist Boko Haram could be guilty of crimes against humanity if they carried out systematic attacks on religious targets, U.N. human rights chief Navi Pillay warned Thursday.

"Members of Boko Haram and other groups and entities, if judged to have committed widespread or systematic attacks against a civilian population -- including on grounds such as religion or ethnicity -- could be found guilty of crimes against humanity," said a statement from Pillay.

Gunmen shot eight people dead in northern Nigeria Tuesday and a mob torched an Islamic school in the south, as a nationwide fuel strike and growing religious tension rattled Africa's oil-rich giant.

The two-day old general strike has not yet affected the output of Africa's top oil producer but it has paralyzed the country and sent the government, already battling a brutal campaign by an Islamist group, into crisis mode.

Nigerian police and protesters clashed on Monday and three people were shot dead as tens of thousands demonstrated nationwide over fuel price hikes and a general strike shut down the country.

The launch of what unions called an indefinite strike came at a crucial moment for Africa's most populous nation and largest oil producer, already hit by spiraling violence blamed on Islamist sect Boko Haram.

Pope Benedict XVI on Monday said peace and reconciliation in Africa remained a "distant" goal, pointing to anti-Christian attacks in northern Nigeria that have killed dozens of people in recent days.

"On the continent of Africa ... it is essential that cooperation between Christian communities and governments favor progress along the path of justice, peace and reconciliation, where respect is shown for members of all ethnic groups and all religions," the pope said in a speech at the Vatican.

Suspected Islamists have shot dead three poker players near a church in the latest attacks targeting Christians in northeast Nigeria, residents said Sunday.

The killings took place late Saturday in Biu town of the northeast Nigerian state of Borno. The area is one of several placed under emergency rule by a presidential decree last week.