Dozens of Nigerian women who were forced to marry Boko Haram fighters were reportedly slaughtered by their 'husbands ' before a battle with troops in the northeast town of Bama . Witnesses said the Islamist militants feared they would be killed by advancing soldiers or separated from their wives when they fled the town . They killed the women to prevent them from subsequently marrying soldiers or other so-called non-believers , they said . Sharifatu Bakura , 39 , said : 'The terrorists said they will not allow their wives to be married to infidels . ' Scroll down for video . The leader of the Islamist extremist group Boko Haram Abubakar Shekau . The insurgents have lost ground to army forces in recent weeks . Nigeria 's military , along with forces from neighbouring Cameroon , Chad and Niger have claimed huge victories over the insurgents in recent weeks but defenceless civilians still face serious threats . The Mother of three said Boko Haram fighters had got word of a military assault on Bama , formerly an Islamist stronghold in Borno state . The insurgents had decided to flee to the nearby town of Gwoza before the troops ' arrival but first decided 'to kill their wives so that nobody will remarry them ' , she said . Mrs Bukara 's husband was killed by the insurgents four months ago but she was spared from a forced marriage because she was visibly pregnant . Boko Haram forcibly married scores of women in Bama after seizing it in September but Nigeria 's military announced its recapture of the town on Monday . Witnesses who were taken under military protection this week to Borno 's capital Maiduguri , 45 miles away , said the killing of women began 10 days before Bama was liberated . The Islamists said 'if they kill their wives , they would remain pious until both of them meet again in heaven , where they would re-unite ' , said Salma Mahmud , another witness . A vigilante who fought alongside the military in the battle to retake Bama , Abba Kassim , said he saw 'dozens of women corpses ' in the town . It has not been possible to verify exact numbers of those killed . Fanna Aisami , 52 , also in Maiduguri after escaping Bama this week , said the executions followed a warning from Boko Haram 's top commander in the town . 'He informed them of the situation and ‎the consequence of the takeover of the town by the advancing troops . 'He warned them that when soldiers killed them they would take their wives back to the society where they would be forced to marry and live with infidels , ' said the mother of seven . The commander 'said it would be better for them to kill their wives and send them to heaven , ' with number of women were shot dead in front of his house , she said . Advances : A photo released by the Nigerian Army shows soldiers in Goniri this week as forces claim a number of victories against the insurgents . Yagana Mairambe , 58 , said some Boko Haram men refused and fled with their wives towards neighbouring Yobe state . Nigeria 's national security spokesman Mike Omeri is working to verify the reports while the military could not immediately be reached for comment . With Boko Haram gunmen facing heavy military pressure across northeast Nigeria , attacks , including suicide bombings , have persisted , even as the government in Abuja tries to assure voters that March 28 elections will be secure . Security operatives search for information at the main gate to the Monday Market where the blast occurred in Maiduguri , Nigeria , earlier this month . The Islamist uprising has claimed more than 13,000 lives since 2009 and President Goodluck Jonathan has faced fierce criticism over failure to contain the violence . The latest reported atrocities in Bama recall similar massacres at high schools and colleges across northeast Nigeria , where Boko Haram has executed scores of students learning a so-called infidel curriculum .
Fighters forcibly married women in Bama after seizing it in September . Women were killed amid fears they would be separated as they fled . Boko Haram fighters did not want them going on to marry 'non-believers ' Islamist forces have recently claimed big victories over the insurgents .