Nigeria faces a prolonged battle to quash the bloody Boko Haram insurgency despite a "hardline" campaign that has witnessed rights abuses by both the state and the militants, according to a South African intelligence assessment obtained by Agence France Presse.

A National Defense Force Defense Intelligence division briefing -- delivered to visiting Chinese Defense Minister Chang Wanquan on Tuesday -- offered a blunt assessment of Africa's crises, including Nigeria's fight against Boko Haram and its Islamist offshoot Ansaru.

Suspected Boko Haram Islamists disguised in army uniforms killed seven people in an attack near the northeastern border with Cameroon, residents said Monday.

The gunmen, five of whom were also killed, razed a police station and a military camp during the late Sunday attack in the restive region, which has been among the hardest hit areas during Boko Haram's five-year uprising.

More than 60 women and girls abducted last month by suspected Boko Haram militants in northeast Nigeria have escaped their captors, sources said Sunday, but more than 200 schoolgirls are still being held by the Islamists.

Local vigilante Abbas Gava said he had "received an alert from my colleagues ... that about 63 of the abducted women and girls had made it back home" late Friday.

Clashes between Nigerian armed forces and Islamists after a daring attack on the military in the country's restive northeast left 53 insurgents and six troops dead, a spokesman announced Saturday.

The rebels attacked barracks and a police station in the town of Damboa, in Borno state, late Friday while most of the troops were out on patrol in surrounding villages, drawing an army response, defense spokesman General Chris Olukolade said in a statement.

Villagers from a northeast Nigerian town where Boko Haram Islamists abducted more than 200 schoolgirls on Friday appealed to the United Nations to intervene because of worsening violence in the region.

The community, which originates from the Chibok district of restive Borno state, claimed militants were running amok in their homeland, seemingly with impunity.

A truck exploded in a huge fireball killing at least 15 people on Tuesday in the northeast Nigerian city of Maiduguri, the latest attack in the area repeatedly hit by Boko Haram Islamists.

The bomb rocked Maiduguri's busiest roundabout near the popular Monday Market during morning rush hour and its force scattered body parts on the rooftops of surrounding shops, according to witnesses.

A Paul Pogba header and a Joseph Yobo own goal saw France edge a hard-fought contest with Nigeria 2-0 in Brasilia on Monday to reach the World Cup quarter-finals.

Pogba broke the deadlock in the 79th minute, nodding into an empty net after Nigeria goalkeeper Vincent Enyeama, who plays for French club Lille, failed to collect a corner.

An attack on churches in northeast Nigeria blamed on Boko Haram killed more than 50 people, an official said on Monday, overshadowing festivities ahead of a last-16 World Cup match against France.

Gunmen stormed Sunday services in four villages near Chibok in Borno state where Boko Haram kidnapped more than 200 schoolgirls on April 14.

Suspected Boko Haram Islamists attacked a series of churches on Sunday near Chibok, the northeast Nigeria town where more than 200 teenage girls were kidnapped in April, with dozens feared dead, witnesses said.

Residents said the gunmen riding on motorcycles opened fire on worshippers and pursued them as they tried to flee into the surrounding bush. 

An explosion in the red light district of northern Nigeria’s Bauchi city has killed 10 people and injured 14 others, police said Saturday.

The cause of the late Friday blast was not immediately clear, but Boko Haram Islamists have attacked Bauchi repeatedly during their five-year uprising aimed at creating a strict Islamic state in the north.