Burkina Faso's government said the Malian army had no authorization to cross into its territory to kill three people during a spate of ethnic violence last week.
Malian officials were not available to comment, but the Malian army said on Saturday that its forces had pursued armed assailants into Burkina Faso.
Under a joint military task force called G5 Sahel, which includes forces from five West African countries, including Mali and Burkina Faso, army units can pursue militants up to 50 km (30 miles) into another member country's territory.