Nigeria and its four neighbouring nations on Saturday pledged to deploy 8,700 troops, police and civilians as part of a regional effort to fight Boko Haram militants.

"The representatives of Benin, Cameroon, Niger, Nigeria and Chad have announced contributions totalling 8,700 military personnel, police and civilians," the countries said in a statement after a meeting in Cameroon's capital Yaounde.

The announcement came out of a three-day summit focused on organising the force that will battle the Islamist militants, who are engaged in a worsening six-year insurgency centred in northeastern Nigeria.

Map of Nigeria locating fatalities as a result of Boko Haram attacks between January 2011 and January, 2015. Reuters However, it may be some time before the multi-national effort goes into action, as nations will continue in coming days to thrash out the details of each government's contribution as well as the budget.

Country representatives at the summit agreed to launch a mission to "foster a safe and secure environment in the impacted regions" and tackle an insurgency that has killed at least 13,000 people and pushed more than a million from their homes since 2009.

African Union leaders will submit the plan for the force crafted by Western and African experts to the UN Security Council for approval.

Boko Haram's attacks have increasingly spilled over from Nigeria into neighbouring nations.

Their first major assault in Niger on Friday triggered a forceful response from Chadian and Nigerien troops.

Niger's defence minister reported that 109 of the Islamists were killed in the fighting, along with four soldiers and a civilian. Seventeen other troops were wounded.

The United States said it condemned the attack in the "strongest possible terms" and pledged support for regional forces.

"This unchecked killing must stop," State Department spokeswoman Marie Harf said. "We continue to provide support to governments in the region, including through intelligence sharing, and are increasing our support for these efforts."

Chad already has troops fighting Boko Haram on two fronts, with soldiers deployed in Niger and Nigeria.

Nigeria's military has drawn fierce criticism for failing to rein in the insurgents, who have intensified attacks ahead of a presidential election.

The Nigerian election commission announced on Saturday that it would postpone the polls, scheduled for February 14, until March 28 over security concerns.

The chairman of the Independent National Electoral Commission, Attahiru Jega, said security chiefs had advised a delay as troops would not be available because of operations against Boko Haram militants.

US intelligence officials said Friday that while Boko Haram is flush with cash and weapons after a string of battlefield advances, the militants could face a tougher fight with Nigeria's neighbours.

The military intervention of neighbouring powers could potentially be a "game changer in a positive way," one intelligence official said.