Suspected Boko Haram gunmen seized two Italian priests and a Canadian nun in northern Cameroon overnight Saturday, in the latest kidnapping of Westerners in the remote, insurgency-wracked corner of west Africa.

The attack occurred overnight in the small parish of Tchere, which lies about 40 miles (60 kilometers) from the corner of northern Nigeria that serves as a base for the Islamist Boko Haram group.

An official in Nigeria's central Nasarawa state and a local leader on Friday accused the military of killing scores of people in a disarmament operation, but defense officials denied the charge.

The alleged incident took place on Thursday in the Keana local government area, where troops were on patrol to enforce a peace deal agreed this week between rival ethnic groups.

Boko Haram leader Abubakar Shekau likely has little control over his fighters, the International Crisis Group said on Thursday, calling the Islamist terror group "more dispersed than ever".

A new report from the Brussels-based think-tank said many of Boko Haram's senior commanders are probably based outside Nigeria, including in neighboring Cameroon and Niger.

Fifteen civilians were killed and 17 others were injured in a suicide attack in northeast Nigeria carried out by suspected Boko Haram militants, the military said on Tuesday.

Defense spokesman Chris Olukolade said one of the victims was a member of a civilian vigilante group and that the blast, on the outskirts of the capital of restive Borno state, Maiduguri, destroyed eight vehicles.

Nigeria's military on Monday denied claims from Amnesty International that its troops may have committed war crimes and crimes against humanity in the fight against Islamist insurgents Boko Haram.

The human rights group has called on the international community to push for an independent investigation into alleged abuses after a bloody three months which have left more than 1,500 dead.

Nigeria's secret police faced questions Monday about how 21 detainees were killed during an attempted jailbreak from their headquarters, with claims of a cover-up about exactly what happened.

The detainees, reportedly suspected Boko Haram insurgents, died Sunday after the Department of State Services said that one inmate overpowered a guard and seized his weapon.

Nigeria's secret police said on Sunday there had been an escape attempt by detainees at their headquarters, with unconfirmed reports that Boko Haram militants were involved.

A breach of security at the secret police facility in Abuja, particularly by the feared Islamists, would be an embarrassment for the government and raise fresh questions about its ability to tackle the extremists.

Renewed violence between herdsmen and farmers in central Nigeria has killed seven, police said on Wednesday, just days after a previous attack that claimed 13 lives.

"We recovered seven bodies following the attack on Agena village yesterday (Tuesday)," Benue state spokesman Daniel Ezeala told Agence France Presse by telephone.

More than 1,000 people have been killed so far this year in three states in northeastern Nigeria worst hit by Boko Haram violence, according to the country's main relief organization.

The National Emergency Management Agency (NEMA) figures are the starkest indication yet of the increase in bloodshed in Borno, Adamawa and Yobe that have caused growing concern.

Renewed violence between herdsmen and farmers in central Nigeria has killed seven, police said on Wednesday, just days after a previous attack that claimed 13 lives.

"We recovered seven bodies following the attack on Agena village yesterday (Tuesday)," Benue state spokesman Daniel Ezeala told Agence France Presse by telephone.