An attack on a military detachment in eastern Burkina Faso has left 33 soldiers dead, the military-led government said, the latest bout of violence in a country locked in fighting against a militant insurgency.

A contingent of troops came across "a complex, large-scale attack" in the Est region on Thursday, which also left 12 soldiers wounded, the army said.

The besieged soldiers killed at least 40 "terrorists" before reinforcements arrived, it said.

Burkina Faso is one of several West African nations battling a violent militant insurgency that has spread from neighbouring Mali over the past decade, killing thousands and displacing over 2 million.

Violence in the country has spiralled in recent months as authorities have struggled to regain ground despite boosting security operations.

Armed forces have also been accused of indiscriminately killing civilians during anti-insurgency missions.

Men dressed in army uniforms killed at least 150 people during a raid on a village in northern Burkina Faso last week, according to the United Nations.

The military government condemned the attack earlier on Thursday and said it would investigate the events.

Armed forces have meanwhile also been accused of indiscriminately killing civilians during anti-insurgency missions.

Frustrations over the authorities' failure to protect civilians spurred two coups last year.