Russia has detained a German citizen on suspicion of explosives-smuggling and terrorism, accusing him of blowing up a pipe at a gas distribution station.
The Federal Security Service said the man, whom it named as Nikolai Gaiduk, had been involved in the attack in Russia's Kaliningrad Baltic Sea exclave in March, using a home-made bomb.
It said he was arrested during a subsequent attempt to enter Kaliningrad from Poland, when authorities searched his car and found half a litre of liquid explosive.
The FSB said Gaiduk was born in 1967 and lives in Hamburg.Â
It accused him of acting on the instructions of a Ukrainian man also living in the north German city.
"Currently, measures are being taken to identify and bring to justice the persons who assisted Gaiduk ... in carrying out illegal activities," the agency said.
The German foreign ministry did not immediately respond to a request for comment.
According to Russia's emergencies ministry, the pipe explosion in March caused a fire but there were no casualties.