The Nigerien President, Mahamadou Issoufou, has sacked the head of the army after two of the country’s deadliest attacks in living memory killed at least 160 soldiers, the government said.

This had prompted a rethink in the battle against militant groups, the official added.

Ahmed Mohamed led the army for over two years, a period marked by a steep rise in attacks by militants linked to Islamic State and al Qaeda.

This had culminated in a daytime raid on a remote army base on Thursday that killed at least 89 soldiers.

That attack came less than a month after another on an outpost that killed 71 soldiers and raised questions about Niger’s ability to contain the spread of militant groups across its western border from Mali and Burkina Faso.

Salifou Modi, a major general, was appointed Mr Mohamed’s successor on Monday, the government announced after a cabinet meeting.

Niger said it would launch a new military offensive against militants, but past campaigns have failed to curb violence in spite of the presence of French and American troops.

Attacks in Niger have raised fourfold over the past year, killing more than 400 people, according to the Armed Conflict Location and Event Data Project, a non-profit research organisation.

Military campaigns by armies in the Sahel, a semi-arid swathe of land beneath the Sahara, have also been marred by human rights abuses, which analysts say have pushed some civilians into the arms of the militants.

In addition to militant attacks, countries in the region, especially Mali and Burkina Faso, have struggled to cope with deadly ethnic clashes between rival farming and herding communities.