Boko Haram militants have driven more than 26,000 people from the northeastern town of Bama amid fierce fighting, witnesses and security sources said on Wednesday, as the Islamists focus more on taking and holding territory.

The government of Borno state, where Bama is located, said it still controlled the town.

As fighting wore on, news came that the insurgency scored another victory on Tuesday by taking the smaller town of Bara, to the southwest roughly halfway between Maiduguri and the national capital Abuja, without firing a shot.

Boko Haram's attacks appear to have shifted focus in recent weeks away from creating mayhem to taking ground and holding it, a strategy analysts say could be inspired by the Islamic State's example of declaring a caliphate in Syria and Iraq.

Last month, the insurgents captured the remote farming town of Gwoza, along the Cameroon border, during heavy fighting. Their leader, Abubakar Shekau, declared in a video that the town was now "Muslim territory."

Boko Haram, a Sunni jihadist movement whose name means "Western education is forbidden," has killed thousands since launching an uprising in 2009 to establish an Islamic state in religiously mixed Nigeria. They are by far the main security threat to Africa's biggest economy.

Ministers from Cameroon, Chad, Niger and Nigeria met in the Nigerian capital on Wednesday to discuss the Boko Haram menace. They "called for greater cooperation of the international community" in fighting the "transfer of arms and ammunitions" to Boko Haram, a statement said.