It's the second such attack in just over a week in which dozens of soldiers have been reported killed.

The military-led government in the capital Ouagadougou spoke for the first time on Thursday about last week's killing of over 100 civilians by what local officials described as men in military uniform.

The government has not said whether the attack on the north-western village of Karma was carried out by the army, but it called for a full investigation.

Non-governmental organisations say over 10,000 civilians and soldiers have been killed in the long-running insurgency, and attacks have sharply increased since the start of this year.