MUNICH, Germany (Reuters) - Islamist militants are increasing their activity in West Africa despite the establishment of a regional force to combat them in the Sahel region, and they are now threatening coastal countries, Burkina Faso’s foreign minister said on Saturday.

Speaking at the Munich Security Conference, Minister Alpha Barry gave a bleak outlook of the situation more than six years after French troops intervened in Mali to stop Islamist militants advancing on the capital Bamako.

The Sahel region has since suffered violence from militant groups linked to al Qaeda and Islamic State, trafficking and the emergence of armed groups in one of the world’s poorest regions.

The northern region of Burkina Faso, bordering Mali and Niger, has over the last 12 months been especially hard hit, leaving the government struggling to assert its authority since President Blaise Compaore was ousted in 2014 in a popular uprising.

“This threat is gaining ground. Yesterday four customs’ officers were killed in south Burkina Faso on the border with Togo,” Barry said.

A Spanish priest was also killed in the incident, which Burkinabe authorities blamed on Islamist militants.

“We’ve also seen attacks on the border with Benin, Ivory Coast and Ghana. It’s no longer just the Sahel, it’s coastal West Africa and the risk of spreading regionally.”

France, the former colonial power in the region, has kept about 4,500 troops in the region and pushed for the creation of a force made up of soldiers from Mali, Niger, Burkina Faso, Chad and Mauritania to combat jihadists.

But the so-called G5 force has been hobbled by delays in disbursing money and poor coordination between the five countries while insecurity has escalated.

Barry said just a fraction of more than 415 million euros ($468 million) promised for the force a year ago had been disbursed, meaning that it had only been able to carry out sporadic operations.

While there have been some operational successes with the help of French troops especially in central Mali, instability has also spread to Niger and Chad, which Paris considers as its most crucial ally in tackling Islamist militants.

This month France sent warplanes to support Chadian President Idriss Deby against a group of rebels, saying it was preventing a coup d’etat.

“The glass is half full,” French Defence Minister Florence Parly said. “It’s complex and we have a lot to do, but I’m convinced we are on the right track.”