Six Chadian soldiers were killed and 10 injured in an ambush attributed to the Boko Haram jihadist group in the volatile Lake Chad region on Monday, the country's army said.

The latest in an intensifying wave of jihadists attacks took place in the afternoon close to Tetewa island in the lake. "Our men were on patrol when they were attacked by Boko Haram elements," army chief of staff Taher Erda said. "Our forces were looking for Boko Haram elements when they were ambushed around Mandrari, a place with lots of tall grass," a local official speaking on condition of anonymity told AFP.

For the last several months jihadist attacks have intensified around Lake Chad, which is riddled with islands and swamps and shared by Chad, Cameroon, Niger and Nigeria. Chad has suffered a particularly heavy toll since the beginning of the year. On January 20 a female suicide bomber killed 9 civilians in the village of Kaiga Kindjiria, near the lake.

Boko Haram was formed in Nigeria but its attacks have spread to neighbouring countries. The group has also split and a faction affiliated with the Islamic State group, ISWAP, is particularly active around Lake Chad. Earlier this month, 1,200 Chadian troops, deployed as part of a regional force in Nigeria, returned to Chad to be redeployed around the lake.

The rising number of attacks has deteriorated the humanitarian situation around the lake, which is considered one of the poorest regions in the world.