“On May 19 the Russian FSB detained a Lithuanian citizen in Moscow, an employee of Lithuanian intelligence,” the service said in a statement posted on Russian news agencies.

“The foreign spy was caught red-handed as he was receiving secret documents from a Russian citizen,” the statement said. “He confessed he is an officer of the Second department… of the military intelligence of the Lithuanian defence ministry.”

“The spy is now in the Lefortovo jail,” in Moscow, it said.

A court later ordered the man — named as Arstidas Tamosaitis — held in custody for two months pending investigations, a court spokeswoman told the Interfax news agency.

The news comes two weeks after Lithuanian prosecutors announced they had detained a Russian citizen suspected of spying and ordered him held for three months.

“The Lithuanian defence ministry doesn’t comment on this kind of information,” defence ministry spokeswoman Asta Galdikaite told AFP Wednesday in Vilnius.

The country, formerly a Soviet republic, has been vehemently opposed to Moscow amid concerns that the Kremlin is aiming to destabilise the Baltic countries following its alleged involvement in eastern Ukraine.

Russia’s relations with the West have tumbled to a post-Soviet low over the Ukraine crisis, as Moscow accuses NATO of closing in on Russia’s borders.