Some 170 people including women and children have been "executed" in attacks on three villages in Burkina Faso, a public prosecutor has said.

Aly Benjamin Coulibaly appealed for witnesses to help find those who attacked Komsilga, Nordin and Soro.

Separately, army chiefs warned of the increased risk of attacks by militants, "including attacks on urban centres".

The country's army seized power in 2022, but more than a third of Burkina Faso is controlled by insurgents.

Mr Coulibaly said he had launched an investigation into the village attacks in Yatenga province on 25 February.

The AFP news agency reported that dozens of women and children were among the dead.

It was not known which group was behind the attacks.

They are not believed to be related to other recent violence - attacks on a church as well as a mosque and army bases - elsewhere in the country.

On Friday, the country's army chief warned soldiers to stay vigilant due to an increased risk of suicide attacks by militants.

He said there were also "fears of a series of large-scale attacks" against security forces in cities.

Humanitarian workers say Burkina Faso is one of the world's most-neglected crises.

Years of rampant insecurity has forced more than two million people from their homes, and the UN estimates that a quarter of all children under five have stunted growth resulting from hunger.

The military seized power two years ago promising to win the battle against rebels, yet the violence continues.

"The epicentre of terrorism has now conclusively shifted out of the Middle East and into the central Sahel region of sub-Saharan Africa," said the Institute for Economics and Peace earlier this week.

The Sahel includes Burkina Faso, Mali and Niger among other nations.