The man, born in 2003, is accused of having “prepared the sabotage of a section of railway line in the city of Nizhny Novgorod with an explosive device” in return for a “financial reward” by Ukraine’s SBU security service, the FSB statement said.

It said “means of communication” found at the suspect’s home had shown messages exchanged with an SBU “representative”.

The arrest comes several weeks after another German citizen, identified as Nikolai Gaiduk, was arrested in the northwestern Kaliningrad region on charges of sabotaging energy installations.

He is alleged to have received the explosive material and orders to carry out the attack from a Ukrainian citizen living in Hamburg, according to the FSB.

Since Russia sent troops into Ukraine in February 2022, there has been a spike in authorities charging people with sabotage, treason and terrorism, including several westerners.

On Nov 20, Germany’s foreign ministry said it knew of at least a dozen cases of German nationals imprisoned in Russia.