Six people, including four civilians, were killed on Thursday in the far north of Cameroon following two incursions by Boko Haram militants, sources told AFP on Friday.

"Boko Haram appeared yesterday (Thursday) around 1900 (1800 GMT) at Assighassia," a police officer in the region said on condition of anonymity. "There followed an engagement between them and our soldiers. Two assailants were killed and one soldier was injured."

Cameroon said on Monday its soldiers had killed "more than 100" Boko Haram fighters during an attempted incursion by the Nigeria-based Islamist insurgents, while across the border thousands continued to flee the group's advances.

Nigeria and its regional allies on Wednesday called for greater international support to shut down Boko Haram's weapons and funding supply as concern mounted at the group's rapid recent land grab.

The call came after conflicting reports that the militants had seized another town, prompting warnings that Nigeria was losing control of the northeast and violence could spill across borders.

Cameroon's army claimed on Tuesday to have killed more than 40 Boko Haram fighters who tried to storm a strategic border crossing from Nigeria.

Heavily armed fighters "attempted to cross the bridge at Fotokol" in the extreme north of the country and opened fire on Cameroonian soldiers, the ministry of defense told state radio. 

Cameroon's army has attacked the Nigerian Islamist group Boko Haram, shelling one of their camps across the border and killing "many" fighters, a security official said on Thursday.

The source said the army had shelled the camp on Wednesday evening, two days after the jihadist group had seized control of the town of Gamboru Ngala on the border with Cameroon.

Boko Haram has seized control of a Nigerian town after soldiers deployed there fled to take refuge across the border in nearby Cameroon, a police source said Tuesday.

"Boko Haram fighters moved into Ashigashya" overnight Monday, where they slaughtered three people in front of a church, a Cameroon police source told Agence France Presse on condition of anonymity.

Hundreds of Nigerian soldiers fled across the border to neighboring Cameroon because of fears of attack from Boko Haram Islamists, Cameroon security sources told Agence France Presse on Monday.

A Boko Haram attack on a border town in northeast Nigeria forced thousands of people to flee on Monday, in a fresh assault indicating the militants' growing ability to strike at will.

The attack on Gamboru Ngala comes after the town was almost entirely destroyed in May in a devastating assault that also left more than 300 people killed and prompted outrage at the lack of military response.

The Nigerian Islamist movement Boko Haram has recruited and trained hundreds of young Cameroonians to carry out attacks in their own country, according to the police and civilians. 

oko Haram gunmen attacked Nigeria's restive northeastern town of Gwoza on Wednesday leaving dozens dead, residents said, in the latest violence blamed on the Islamists.