Russia's domestic security agency says it has arrested a Lithuanian citizen suspected of spying.

The Federal Security Service, the main KGB successor agency known under its Russian acronym FSB, said the suspect was caught Tuesday while receiving classified documents from a Russian man. It said in a statement that the suspect admitted being an officer of Lithuanian military intelligence and was put in Moscow's Lefortovo jail.

The agency offered no further details.

The Lefortovo Disctrict Court in Moscow said in Wednesday's statement that it sanctioned the arrest of the suspect, whom it identified as Arstidas Tamosaitis.

The arrest is the latest in a series of spy cases amid tensions between Russia and the West over Ukraine.