The Mauritanian army on Friday "completely destroyed" a camp of the al Qaeda in the Islamic Maghreb (AQMI) in neighbouring Mali in an assault which left four soldiers wounded, a security source told AFP.
The attack in the forest region of Wagadou in western Mali involved air strikes and was staged in the evening, the source said, adding that the "terrorists" struck back with "heavy arms."
"The definitive toll on the enemy side will only be known at dawn but it will be heavy ... The tents of the camp and three vehicles have been destroyed," she said.
Earlier this month, Mali and Mauritania agreed to lead a joint military operation to thwart al Qaeda's north African offshoot.
AQIM members have been regularly spotted in the region, suggesting it has become a base for the group.
Mali and Mauritania have previously expressed concerns about the activities of the group along with Nigeria and Algeria.
The outfit has several bases in Mali from where it launches operations in the Sahel desert region, carrying out attacks, kidnapping foreigners and trafficking drugs.