SEVASTOPOL, Ukraine -- A Russian national suspected of spying for Ukraine has been arrested in the Russian-occupied region of Crimea.
The Lenin district court in the city of Sevastopol said on April 22 that "a Russian citizen born in 1998" suspected of high treason had been placed under pretrial arrest until at least June 19.
Earlier in the day, Russia's Federal Security Service (FSB) said its officers had detained a person who "passed classified information about Russia's Black Sea Fleet to Ukrainian military intelligence."
No further details of the case were made public.
Russia seized Ukraine's Crimean Peninsula in March 2014, sending in troops and staging a referendum denounced as illegitimate by at least 100 countries after Moscow-friendly Ukrainian President Viktor Yanukovych was ousted amid a wave of public protests.
Since then, Russia has arrested dozens of people in Crimea on charges including extremism, terrorism, and espionage.
Rights groups have said that after imposing its control over the region, Moscow aggressively moved to prosecute Ukrainian activists and anyone who questions the annexation.
Russia also backs separatists in a war against Ukrainian government forces that has killed more than 13,000 people in eastern Ukraine since April 2014.