Jihadist group Islamic State said on Thursday it had killed 13 Nigerian soldiers and five troops from a west African anti-militant force in attacks over recent days.

Islamic State West Africa Province (ISWAP), which split from Nigeria-based Boko Haram in 2016, has carried out a series of attacks in the last few months.

In its newspaper Al-Nabaa, IS said its fighters killed the Nigerians in attacks on a military barracks on Friday, a military post on Sunday, and a town on Monday, all in northeastern Borno state.

Fighters also detonated explosives on Wednesday on a vehicle in the Lake Chad region, killing five more soldiers, IS said, without specifying the country.

The militants said the vehicle was carrying troops from a multinational task force – comprising of troops from Nigeria, Niger, Chad and Cameroon – set up to fight them.

A Nigerian military spokesperson declined comment and a spokesperson for the task force could not immediately be reached.

Boko Haram has waged a decade-long insurgency in northeast Nigeria which has killed around 30 000 people and forced about two million to leave their homes.