By Daniel Flynn and Lanre Ola
N'DJAMENA/MAIDUGURI, Feb 19 (Reuters) - Nigerian warplanes bombed training camps and equipment belonging to Islamist group Boko Haram in the northeast's Sambisa forest on Thursday, the military said, adding momentum to an assault meant to crush the rebels also involving neighbors Chad, Cameroon and Niger.
"The death of a large number of terrorists has been recorded while many others are also scampering all over the forest," defense spokesman Major-General Chris Olukolade said, later adding that an attack was underway on parts of Gwoza, the town where Boko Haram first declared an Islamic state last year.
After a year in which Boko Haram seemed to be gaining ground, seizing swathes of territory, killing thousands of people and kidnapping hundreds of mostly women and children, the tide may now be turning against them, as neighboring countries plagued by cross-border attacks have weighed in.
Niger, Chad and Cameroon are seeking to pin down Boko Haram within Nigeria's borders ahead of a ground-and-air offensive by a regional task-force due to start from the end of next month, a senior Niger military official said.
Sambisa gained notoriety last year when more than 200 girls kidnapped by Boko Haram from a secondary school in nearby Chibok were taken there. Some of them escaped the forest shortly afterwards but most have remained in captivity ever since.
Aerial surveillance of the forest has not revealed their whereabouts. If some or all are still in the forest, air strikes against the rebels holding them captive could have grave risks.
Military chiefs will meet in Chad's capital N'Djamena next week to finalize plans for a 8,700-strong task-force of troops from Chad, Cameroon, Nigeria, Benin and Niger to fight the Islamists, although it is unclear how good coordination will be.
"PUSH THEM BACK"
Nigerian forces backed by air power killed more than 300 Boko Haram fighters during an operation to recapture 11 towns and villages since the start of the week, the military said on Wednesday, though it was not possible to corroborate this and the military has been accused of exaggerating enemy casualties and understating its own and those of civilians.
Successes in pushing back Boko Haram would come at a welcome time for Nigeria's President Goodluck Jonathan, who faces an election on March 28. The poll however also provides a strong motive for the government and military to talk up successes.
The election had been delayed by six weeks on the advice of the military and Jonathan has been repeatedly criticized for not doing enough to tackle the rebels.
"We will rout Boko Haram. Our capacity to achieve results in the northeast has increased sufficiently," Jonathan told the navy in Lagos on Thursday, commissioning four new warships. "Our men and officers are doing well in the northeast and we must conduct the elections as scheduled."
The risk to civilians from air strikes was highlighted on Tuesday, when an aircraft bombed a border village in Niger, the Niamey government said. A Nigerian security source said on Thursday that the plane was Nigerian and that the pilot had mistaken the civilians for fleeing insurgents.
"This worrying incident must be promptly investigated by both Niger and the (multinational force)," Corinne Dufka of Human Rights Watch said, urging the force to "ensure the ongoing offensive is carried out in a way that protects civilians."
The militants fighting to revive a medieval Islamic caliphate in northeast Nigeria for the past six years remain the biggest threat to Africa's top economy and the whole region.
Boko Haram struck a village in southeast Niger overnight, killing three people including the local chief and wounding three others before troops drove them out.
"All we are doing right now is stopping Boko Haram from entering Niger," Colonel Mahamane Laminou Sani, director of documentation and military intelligence of Niger's armed forces told Reuters in N'Djamena. "If they attack our positions we push them back a certain distance and Nigeria pushes from the other side to contain the situation."
(Additional reporting by Felix Onuah in Abuja, Tim Cocks in Lagos, David Lewis in Dakar and Abdoulaye Massalaki in Niamey; Writing by Tim Cocks; Editing by Giles Elgood)