Boko Haram on Wednesday launched a pre-dawn raid in Gamboru, northeastern Nigeria, looking to overwhelm Chadian troops who had pushed them out of the border town.

The military in N'Djamena said the militants were repelled but the counter-attack was an indication of the task facing regional forces aiming to crush the rebellion.

Suspected members of Boko Haram kidnapped 20 people from a bus in northern Cameroon, then executed 12 of them, a security source and resident said Monday.

The kidnapping occurred on Sunday and all of the survivors have since been released, said a resident, on condition of anonymity, whose wife was among those abducted. An official from a local NGO also confirmed the incident.

Niger is set to send troops to Nigeria for the multi-national battle against Boko Haram after scores of people were killed in a fresh onslaught by the Islamist fighters in a key border town.

Intervention from Niger would open a new northern front in the increasingly regional fight against the Islamist insurgents who killed more than a hundred people, including 19 soldiers, on Wednesday in a rampage in the Cameroonian town of Fotokol on Nigeria's border.

Niger is set to send troops to Nigeria for the multi-national battle against Boko Haram after scores of people were killed in a fresh onslaught by the Islamist fighters in a key border town.

Intervention from Niger would open a new northern front in the increasingly regional fight against the Islamist insurgents who killed over a hundred people, including 19 soldiers, on Wednesday in a rampage in the Cameroonian town of Fotokol on Nigeria's border.

Thirteen Chadian soldiers were killed on Wednesday in a counter-attack by Boko Haram militants on the Cameroonian border town of Fotokol, Cameroon's defense minister said.

"After finishing the count in Fotokol, we...  found 13 Chadian soldiers killed," the minister, Edgar Alain Mebe Ngo'o, said Thursday. 

Boko Haram fighters killed nearly 70 civilians and six soldiers in an onslaught on the Cameroonian border town of Fotokol on Wednesday, a Cameroonian security source told AFP.

"There are many (dead) civilians, nearly 70. The toll for the soldiers stands at six," said the source in Fotokol, adding that there were also  Boko Haram bodies "everywhere".

Nigerian Boko Haram fighters went on the rampage in the Cameroonian border town of Fotokol Wednesday, massacring civilians and torching a mosque before being repelled by regional forces.

The onslaught came a day after Chad sent troops across the border to flush the jihadists out of the Nigerian town of Gamboru, which lies some 500 meters (yards) from Fotokol on the other side of a bridge.

Thousands of Nigerian civilians who fled the armed Islamists of Boko Haram have become a headache for Chadian authorities after seeking safety on a multitude of scattered islands in Lake Chad.

"We waded through the water for several days and suffered so much," recalled former taxi driver Adamou Bouba, who snatched up his toddlers, aged two and three, when Boko Haram fighters raided his village, Kiguili, and killed his wife.

Three soldiers and 123 Boko Haram militants were killed when the Islamist group attacked a Chadian army contingent in northern Cameroon, the Chadian military said Friday.

Twelve soldiers were wounded in the attacks staged by the Islamists on Thursday and Friday near the border town of Fotokol, according to a military statement read out on national television.

Cameroon said Wednesday its forces have freed a German hostage kidnapped six months ago in Nigeria by Boko Haram, as African leaders appealed to the United Nations for support in fighting the Islamist militants.  

"A special operation led by Cameroonian armed forces along with security services of friendly nations succeeded this night (Tuesday) in freeing Nitsch Eberhard Robert, a German citizen abducted in Nigeria in July 2014 by the Boko Haram sect," the Cameroon presidency said in a statement.