Seven children and four women were among 14 civilians, killed when a roadside bomb blew up their bus in northwestern Burkina Faso, the government said.

"The provisional toll is 14 dead," a statement said, adding that 19 more people were hurt, three of them seriously in Saturday's blast.

The explosion happened in Sourou province near the Mali border as students returned to school after the Christmas holidays, a security source said.

The bus was among a convoy of three that was carrying 160 passengers in all.

"The government strongly condemns this cowardly and barbaric act which aims to damage people's morale," the statement said.

"The vehicle hit a homemade bomb on the Toeni-Tougan road," AFP reported.

It's not immediately clear who was behind the attack but assailants with links to al Qaeda and ISIL have increased attacks over the past two years.

Insurgents killed 35 mostly female civilians on December 24 after attacking a military outpost in Soum Province, also in the north. About 87 militants and local security officers were killed in the clash, authorities said.

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(Cover: Burkina Faso soldiers patrol on the road of Gorgadji in the Sahel area in March 2019. /Reuters Photo)