The incident occurred during an operation to "track down and neutralise armed individuals, combat cannabis cultivation and ensure the safety of the population and their property", the military said in a statement.

The three soldiers died "in an accidental explosion that occurred early Tuesday morning" while carrying out operations "to destroy cannabis fields along the border with The Gambia", it said.

It did not provide further detail on the nature of the explosion but said operations in the area would continue "resolutely".

It added that the three wounded soldiers were evacuated and "receiving medical treatment".

The operation, which began more than a week ago, has so far resulted in "the neutralisation of several individuals belonging to armed groups engaged in cannabis cultivation and threatening the peace of the local population".

Last week the military reported that one soldier was killed and six others wounded in Casamance after military personnel carrying out cannabis clearing operations "engaged with a group of armed individuals in the Kadialock area".

Officials accuse rebels in Casamance of illicitly trafficking cannabis and wood, and of seeking refuge in The Gambia or Guinea-Bissau to the south.

Casamance has hosted one of the longest ongoing conflicts in Africa since armed separatists withdrew to the bush after protests in December 1982.

Having claimed thousands of lives and devastated the economy, the conflict has persisted but on a much-diminished level in recent years.