More than 1,000 civilians have been killed in Boko Haram attacks in the first three months of this year, Human Rights Watch said on Thursday.

"Each week that passes we learn of more brutal Boko Haram abuses against civilians," the group's Nigeria researcher, Mausi Segun, said in an emailed statement.

Sixteen Cameroonians have been kidnapped in northeastern Cameroon in an alleged attack by armed militia from the Central African Republic (CAR), security sources said on Friday.

The attack took place on Thursday night in Gbabio village, near the border with the CAR, and is thought to have been led by rebel chief Abdoulaye Miskine.

Chadian troops deployed to fight Boko Haram in Nigeria have returned to Cameroon, where they are expected to be regroup for fresh offensives in border areas, military sources said on Friday.

Some 2,500 troops deployed as part of a regional force against the Islamist militants have in recent weeks retaken the towns of Gamboru and Dikwa, in Borno state, northeast Nigeria.

The African Union has endorsed the creation of a regional force of up to 10,000 men to join the fight against the Nigerian Islamist group Boko Haram, diplomats said Friday.

The force, the idea for which was adopted at an AU summit in January, will be based in Chad's capital N'Djamena, the pan-African bloc's Peace and Security Council said.

A homeless man controversially shot dead by police in Los Angeles was from Cameroon, and had stolen the identity of a Frenchman, U.S. and French officials said Wednesday.

The LA Times had initially identified the victim -- killed Sunday in a shooting caught on a video which went viral -- as Charley Robinet, saying he was French, but the French foreign ministry denied this.

Bomb attacks in Nigerian towns and cities look likely to increase in the run-up to forthcoming elections, despite the military claiming increasing successes against Boko Haram in captured territory.

At least 86 people were killed in explosions blamed on Boko Haram this week alone, all of them at crowded bus stations in the northeast, wider north and also in the country's central region.

Boko Haram militants suffered heavy casualties when Chadian troops pushed into Nigeria this week, residents who fled the fighting told Agence France Presse on Thursday.

Chad's army said on Tuesday evening that they had seized control of the town of Dikwa, which is about 50 kilometers (31 miles) southwest of the Nigerian border town of Gamboru.

Four African armies, from Nigeria, Cameroon, Chad and Niger, are currently directly engaged in the fight against the Nigeria-based insurgent group Boko Haram.

Regional forces have gone into action while awaiting the formation of a planned 8,700-strong, five-country force, whose make-up remains to be determined.

Cameroon's army says it has killed 86 Boko Haram militants and detained 1,000 people suspected of links to the Islamist group, as central African leaders held talks on how to combat its bloody insurgency.

Five Cameroonian soldiers were also killed during the clashes in the Waza region near the border with Nigeria, defense ministry spokesman Didier Badjeck said Monday.

Central African leaders began talks Monday in Cameroon's capital Yaounde on a joint strategy to tackle the extremist Boko Haram group, officials said.

Six heads of state attended the meeting held under the aegis of the Economic Community of Central African States (ECCAS), while four other countries sent delegates.