In a statement, army headquarters said "targeted actions" were carried out in the east on Monday against "terrorist groups responsible for several atrocities".

"During these operations, which enabled several dozen terrorists to be neutralized, the strikes unfortunately caused collateral victims among the civilian population," it said.

The civilians were close to a jihadist hideout on the Kompienga-Pognoa highway when they were hit by "projectiles", the text said.

It gave no other details, but expressed "sincere condolences" to relatives of the dead and said an inquiry had been launched.

Local residents said around 30 people had died, most of whom were women.

"They had gathered for the inauguration of a mill when the tragedy happened," said one, speaking on condition of anonymity.

Monday's operations were undertaken at Djamanga, Djabiga, Mandeni, Bounou, Obiagou and Pognoa-Sankoado, the army statement said.

The military typically use the term "terrorist" for armed groups behind a ruthless jihadist insurgency.

One of the poorest countries in the world, Burkina Faso first came under attack in 2015 from militants operating in neighbouring Mali.

Since then thousands of people have died, around two million have been displaced and more than a third of the country's territory lies outside government control, according to official figures.

Attacks have increased since the start of the year, despite a coup by colonels whose declared priority is to restore security.

Air raids have been increasingly used against the jihadists in recent months.

The army has previously acknowledged the death of a civilian which it said occurred on June 11 during a strike on armed traffickers in the south. Military prosecutors have opened an inquiry.