Nigeria's army and Boko Haram militants have engaged in a fierce gun battle in the north-eastern Borno state, reportedly leaving scores dead on either side.The army says it killed 150 militants, while 16 soldiers died and nine more are missing.However, local media report that around 100 soldiers may have died.BBC Nigeria analyst Bashir Abdullahi says it is clear that the army still faces a tough battle with Boko Haram.He notes that the military often plays down its own casualty figures.Army spokesman Ibrahim Attahiru said a heavily guarded militant base in the Kasiya forest north of the state capital Maiduguri was raided on 12 September - this is the first time the details have been made public.Brig Attahiru said the militants had gathered at a "well fortified position with anti-tank and anti-aircraft guns mounted on vehicles".map He also said that a militant commander, Abba Goroma, who had a bounty of 10m naira ($62,000; £39,000), was among those killed.Communications with Borno state have been severely disrupted since May, when a state of emergency was declared in Borno and two neighbouring states.Boko Haram has not commented on the reports.Several thousand people have been killed since the militant group launched its insurgency in 2009, seeking to create an Islamic state in the mainly Muslim north of Nigeria.Under the state of emergency thousands of extra troops have been sent to the area.Local vigilante groups have also been formed to help counter the militants but scores of these volunteers have been killed in recent weeks.Last month, the army said it had killed Boko Haram's leader Abubakar Shekau but this has not been confirmed and the militants' attacks have continued.Brig Attahiru also said that President Jonathan had ordered the deployment of extra troops to the central state of Nasarawa, east of the capital Abuja, following ethnic clashes which have left a reported 50 people dead in recent days.A picture taken from a video distributed to Nigerian journalists in the country"s north in recent days through intermediaries and obtained by AFP on March 5, 2013 shows Abubakar Shekau (C), the suspected leader of Nigerian Islamist extremist group Boko Haram, flanked by two armed and hooded fighters in an undisclosed place.