Gunmen killed six people including a priest outside a Catholic church in Burkina Faso on Sunday, a local official said, the second attack on Christians in two weeks in a nation increasingly overrun by jihadists.

Congregants were leaving church around 9 a.m. (0900 GMT) when about twenty men encircled them and shot six dead, Boucary Zongo, mayor of the northern town of Dablo where the attack took place, and a witness, told Reuters.

The attackers then burned the church, looted a pharmacy and some other stores, and left in vehicles, they said.

Burkina Faso has been beset by a rise in attacks in 2018 as groups with links to Islamic State and al Qaeda based in neighbouring Mali seek to extend their influence over the porous borers of the Sahel, the arid scrubland south of the Sahara.

The government declared a state of emergency in several northern provinces bordering Mali in December because of deadly Islamist attacks.

But violence has only worsened since. Two French soldiers were killed in an operation to rescue four people taken hostage in Burkina last week, France said.

Roughly 55% to 60% of Burkina Faso's population is Muslim, with up to a quarter Christian. The two groups generally live in peace and frequently intermarry.

Then in late April unidentified gunmen killed a pastor and five congregants at a Protestant church, also in the north, suggesting the violence was taking a religious turn.