(Changes sourcing, recasts, adds details, quote from video)

MOSCOW, Dec 10 (Reuters) -

Russia's Federal Security Service $(FSB)$ said on Tuesday it had detained a dual Russian-German citizen on suspicion of preparing an act of sabotage on a railroad in Nizhny Novgorod, a city some 280 miles (450 km) east of Moscow.

The FSB did not name the man, but said he was born in 2003. It said authorities had found an improvised explosive device (IED) at his home, as well as evidence he had corresponded with a member of Ukrainian special services.

Ukraine's military intelligence and state security service did not immediately reply to requests for comment.

Russian officials have linked pro-Ukrainian sabotage groups with numerous attacks on railways aimed at disrupting supplies to the battle front in Ukraine since the war began in February 2022.

Ukraine's domestic spy agency has also been accused of detonating explosives on railway lines inside Russia.

Russian military news outlet Zvezda published video on Tuesday purporting to show the Russian-German man, whose face was blurred out, confessing to the crime. It was not clear if the man confessed under duress.

In the video, he said he had arrived in Russia in 2023 and had met a man named Artyom online, who turned out to be "a member of the Ukrainian special services".

He said the man paid him to set fire to a fuse box and draw pro-Ukrainian graffiti. "The last task he proposed to me was to blow up, well, derail a train, a freight train," the man said in the video.

The FSB said a criminal case had been opened against him. It said it had detained other individuals alongside the Russian-German national, but did not provide details on them.

The German foreign ministry did not immediately respond to a comment request.

Last month, the FSB

detained

German citizen Nikolai Gaiduk on suspicion of explosives-smuggling and terrorism, accusing him of blowing up a pipe at a gas distribution station in Russia's Kaliningrad Baltic Sea exclave earlier this year.

(Reporting by Reuters; Writing by Lucy Papachristou; editing by Guy Faulconbridge and Mark Trevelyan)

((Lucy.Papachristou@thomsonreuters.com;))