As many as 40 Chadian soldiers were killed when Boko Haram insurgents launched a surprise attack on their military unit in Lake Chad province, near the Nigerian border.
The Chadian government said the unit had been dispatched to set up an army outpost on the island of Bouka-Toullorom, where Boko Haram has carried out several offensives in recent years.
The outpost, between the villages of Ngouboua and Kaiganear Ngouboua, is part of a military reorganisation to deal with jihadists.
Reports said numerous Boko Haram fighters attacked the unit in successive waves, managing to enter the outpost – which they destroyed – before stealing weapons.
The death toll is still to be confirmed, with the Chadian presidency referring to some 20 dead and wounded soldiers. Other sources said at least 35 had been killed, with several more soldiers missing.
Those same sources said the jihadists had also killed at least four civilians as they retreated to their hideouts.
The Boko Haram insurgency, which erupted in northeast Nigeria in 2009, has killed more than 350,000 people and forced millions to flee their homes.
The group has spread to the swampy Lake Chad zone in the west of the country, where the armies of Chad, Nigeria and Niger have been fighting the Islamist militants for years.
Despite efforts to push them back, Boko Haram militants killed 92 Chadian soldiers and wounded 47 more in March 2020.