Russia arrests German man accused of sabotage plot

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. 

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.