"We have the number of 14 deceased and 24 injured, including seven in a critical state," said Salif Traore, giving no further comment on the attack or on who might be behind it.
The remote border region where Burkina Faso, Mali, and Niger meet has become a haven for Islamist militants, who often launch deadly attacks on United Nations, Malian and international troops. Improvised explosive devices (IEDs) have been commonly used.
The vehicle hit the landmine while carrying 60 passengers through an area where ethnic militias regularly kill civilians from rival groups and Islamist militants are also active.
A person at the scene told Reuters his sister and nephew had been on board the vehicle and were killed in the explosion.
"The army is trying to recover bodies from under the bus," he said, speaking by telephone on condition of anonymity.