Russia's security service (FSB) accused a resident of Tyumen in Siberia of handing military information to Ukraine and detained him, state-run news agencies reported Wednesday.
This is the latest in a string of treason or espionage cases linked to Ukraine, with trials often held behind closed doors and few details seeping through.
The FSB said a resident of the Siberian region of Tyumen had sold Ukraine information on military facilities located in his region, according to a report from TASS.
He was placed in pre-trial detention, TASS said, and risks up to life imprisonment.
Investigators launched a case into "high treason in the form of helping a representative of another state commit activities against the security of Russia," according to the FSB statement cited by TASS.
Russian authorities have increasingly arrested citizens on suspicion of high treason, as well as sabotage or spying for Ukraine.
The cases are often classified as secret, meaning there is little information available, fueling fears from Russian rights groups that the charges are fabricated.