ABUJA (Reuters) - West African troops killed 42 suspected Islamic State fighters in a battle in the Lake Chad region on June 21, the heaviest death toll suffered by the insurgents in the last six months, a regional military task force said in a statement.

The Multinational Joint Task Force (MNJTF) comprising troops from countries bordering the lake - said one of its soldiers was killed and 10 others were injured.

In an apparent reference to the same clashes, Islamic State said its fighters had killed 15 soldiers in fighting on June 21 at Garno, a town in Nigeria’s northeastern Borno state near Lake Chad. It said a suicide bomber detonated an explosive device but did not refer to any of its fighters having been killed.

Islamic State West Africa Province (ISWAP) was formed in 2016 when a faction of Nigerian Islamist group Boko Haram pledged allegiance to Islamic State. The insurgency has affected countries that border Lake Chad - Nigeria, Niger, Chad and Cameroon, as well as islands on the lake itself.

The MNJTF said in a statement issued on Saturday that “42 terrorists (were) neutralized” during fighting on and around a Lake Chad island called Doron Naira. It said it meant it had “inflicted the heaviest loss in 6 months on ISWAP”.

Islamic State, in a statement issued through its Amaq news agency, said: “Fifteen African coalition soldiers were killed and others injured when Islamic State fighters attacked them.”

The insurgency, which began in northeast Nigeria, has killed more than 30,000 people and displaced about 2 million since 2009.