Militants killed 15 Burkinabe soldiers and volunteer militiamen as they returned from a supply mission in eastern Burkina Faso, the army has said.
According to international media reports, A further four soldiers were wounded in the attack in Gourma province, while 11 are still missing, it said in Sunday's statement.
"Reinforcements have been deployed to secure the zone and carry out a search," a source told reporters.
The unit that came under fire had been sent to relieve a detachment from Natiaboani.
The army added it killed 18 "terrorists" in mopping-up operations. Dozens of truck drivers are still missing.
The authorities also launched a drive to recruit 50,000 civilian defence volunteers to back up the army as the number of attacks increases.
