Authorities in Ukraine have detained a priest who used missions to the country’s conflict-ridden east to traffic arms, including a grenade launcher and hand grenades.

The cleric was detained several months ago in north-western Ukraine, but his detention was only made public after further police investigations, the Ukraine security services (SBU) said. “It is a very delicate topic,” said an SBU spokeswoman, Olena Gitlyanska.

Investigators said, from 2015, the priest, who has not been named, carried out repeated “preaching missions” to eastern Ukraine, where government forces have been fighting separatists backed by Russia. “He returned with dangerous trophies, which he sold to friends,” the SBU said.

On several occasions the priest sold weaponry, the authorities said, including a rocket-propelled grenade launcher, seven grenades and 800g of dynamite.

The man faces up to seven years in prison.

The case highlights the problem of illegal weapons trafficking, which has escalated since 2014 when fighting broke out between the Ukraine government and separatists in the eastern Donetsk and Lugansk regions.

Russia annexed the Crimean peninsula from Ukraine in 2014, a move that was met with tough economic sanctions by western countries. More than 13,000 people have been killed in fighting since.