ABUJA (Reuters) - Conflicting accounts emerged on Monday of an attack by Islamists on the Nigerian military last week, with security sources saying as many as 48 soldiers had been killed but state media quoting an official army spokesman as saying such reports were wrong.

FILE PHOTO: A military vehicle drives along the Konduga-Bama road in Bama, Borno, Nigeria, August 31, 2016. REUTERS/Afolabi Sotunde/File Photo

Thursday’s attack by suspected members of Islamic State in West Africa (ISWA), on a base in Zari village in the north of Borno State, is the latest blow to Nigeria’s efforts to defeat Islamist insurgencies.

In 2016 ISWA split from Boko Haram, the jihadist group which has killed more than 30,000 people in the region since 2009, when it launched an insurgency to create an Islamic caliphate.

Military and security personnel who did not want to be named told Reuters on Saturday up to 30 soldiers had been killed in the Zari attack. Three such sources said late on Sunday and on Monday the known death toll of Nigerian troops had risen to 48.

Military spokesmen did not respond to phone calls and text messages from Reuters on Monday requesting comment.

Army spokesman Texas Chukwu told the state-run News Agency of Nigeria (NAN) on Sunday there had been a firefight between troops and insurgents. But he called the reports of killings of soldiers a “figment of the imagination of the news agency”, without saying which news agency he meant.

Reports of killings of troops have been published by foreign news organizations including Reuters and by some Nigerian media.

“During the firefight, the overwhelming volume of fire was unleashed on the insurgents from both the air and ground troops, neutralizing several of them and their weapons,” Chukwu told NAN. He did not specifically say that no government troops had been killed.

President Muhammadu Buhari, a former general, won the 2015 election after vowing to crush Islamist militants. He plans to seek a second term in February.

Buhari said on Sunday Boko Haram were no longer in Borno state and did not control any territory, according to a presidency statement.