The FSB, Russia's Federal Security Service claimed that a Ukrainian citizen was detained in Simferopol, in the annexed Crimea. The authority's press department reported that on Monday.
'On February 11, the FSB detained Kostyantyn Davydenko, the citizen of Ukraine... the mentioned individual appears to have intentionally collected secret information about the activities of the National Guard and the Federal Security Service of the Russian Federation', the message says.
The service opened the criminal case against Davydenko, accusing him of espionage.
Neither Ukraine's foreign ministry nor any other governmental agencies commented on the detention.
Russia illegally annexed Crimea in March 2014; Ukraine and the vast majority of civilized countries never recognized the annexation, claiming that the peninsula remains part of Ukraine. The Russian political leadership and leading enterprises faced sanctions from the EU and the U.S.
Since the annexation, Russian authorities of Crimea have been frequently searching and detaining local residents. Human rights activists threat this as a 'crackdown on dissent'.