Baek Won-soon was detained in Vladivostok earlier this year, the last foreign citizen imprisoned in Russia.
Russia detained a South Korean in the east of the country, accusing him of espionage.
Citing authorities, Russia's state news agency TASS identified the man as Baek Won-soon and said he had been detained in the city of Vladivostok “at the beginning of the year,” before being transferred to Moscow for “investigative actions.” . at the end of last month.
Baek, whose case has been classified as “top secret”, is being held in Lefortovo prison, where a court on Monday ordered his detention extended until June 15, TASS said.
The agency cited an unnamed law enforcement official as saying that Baek had passed information “constituting state secrets to foreign intelligence services.” No further details were made public.
South Korea's Foreign Ministry said in a statement that its consulate had been providing assistance since becoming aware of Baek's detention. He declined to elaborate on the matter, citing the ongoing investigation.
The Yonhap news agency's Korean service said Baek was a missionary who had participated in rescuing North Korean defectors and providing humanitarian aid. He was detained in January, just days after arriving in Vladivostok by land from China, the agency added.
The incident marks the first time a South Korean has been detained in Russia on charges of espionage.
Russia labeled South Korea an “unfriendly” country in 2022 due to its support for Western sanctions against Moscow over its invasion of Ukraine.
Russia has also deepened its relations with North Korea after leader Kim Jong Un traveled to Russia last September and met with Russian President Vladimir Putin.
The United States and others have accused North Korea of providing weapons to Russia for use in its war in Ukraine in exchange for technological know-how to advance Pyongyang's military modernization program.
Both countries have denied the accusations.
Over the past year, Russia detained several foreign nationals and accused them of committing various crimes.
American journalist Evan Gershkovich was arrested for alleged espionage in March 2023 and is also being held in Lefortovo prison, known for its harsh conditions and for keeping detainees in almost total isolation. His detention has been extended until the end of March and the judicial process has been held behind closed doors.
In October, Russian-American journalist Alsou Kurmasheva was detained for failing to register as a foreign agent and later charged with spreading “false information” about the Russian military. His detention has been extended until April.
Espionage carries a maximum prison sentence of 20 years in Russia.
Gershkovich and Kurmasheva deny the charges against them.
