Six Chadian soldiers were killed and 10 others were injured in an ambush by suspected Boko Haram militants near Tetewa Island in the Lake Chad region on Monday, according to the army.

Chad's army chief of staff Taher Erda said that the soldiers were on patrol when they were attacked by Boko Haram elements.

"Our forces were looking for Boko Haram elements when they were ambushed around Mandrari, a place with lots of tall grass," a local official also told AFP on condition of anonymity.

The number of jihadist attacks around Lake Chad, which is shared by Chad, Cameroon, Niger and Nigeria, has increased in recent months.

Just over a week ago, a female suicide bomber killed 9 civilians in Kaiga Kindjiria village near the lake.

In December, suspected Boko Haram militants killed at least 50 people on an island on Lake Chad, bordering Cameroon and Chad, according to an official.

Earlier this month, Chad ended a months-long mission fighting Boko Haram in neighboring Nigeria and withdrew its 1,200-strong force across their common border.

Boko Haram began the insurrection in Nigeria a decade ago, leading to at least 35,000 deaths with violence spilling over into Chad, Niger and Cameroon.

A Boko Haram faction aligned with Islamic State West Africa Province (ISWAP) jihadists is highly active around Lake Chad where the group has training bases on the Niger border and regularly carries out raids on military bases and regional security forces.