Jihadists linked to the Islamic State group killed 14 Nigerian soldiers in an attack on an army base near northeast Nigeria's main city, military sources said Saturday. 

Two sources said on condition of anonymity that fighters from the Islamic State West Africa Province (ISWAP) group had attacked the base in Jakana on Friday evening, firing machine guns and rocket-propelled grenades. 

"We lost 14 soldiers in the fight, including the commanding officer and another officer," one source said. Several other soldiers were missing and presumed to have either escaped or been captured by the militants, said the second source who gave the same toll. 

The sources asked not to be identified as they were not authorised to speak.  The insurgents seized four trucks fitted with machine guns in the raid, the sources said. Jakana, 25 kilometres (15 miles) from regional capital Maiduguri, lies on a known crossing route for ISWAP fighters moving between their camps in the Benisheikh forest area of Borno and their hideouts in the Buni Yadi area of Yobe.

The village and the base have repeatedly been raided by the jihadist fighters who splintered from the main Boko Haram group four years ago. Since the split, ISWAP has intensified attacks on military targets, raiding bases and ambushing soldiers. On Monday the Nigerian military began an extensive military operation against ISWAP in an area between Borno and Yobe which included Jakana.

It was not clear if the raid was in response to the military offensive. On Friday ISWAP claimed to have killed 30 troops when its fighters repelled an attack on their position in Doksa village in Borno's Damboa district

At least 36,000 people have been killed and around two million displaced in the decade-long Islamist conflict in northeast Nigeria. The violence has spread to neighbouring Niger, Cameroon and Chad, leading to the formation of a regional military force to fight the insurgents.