SUWON, South Korea — Russian authorities for the first time detained a South Korean citizen on espionage charges earlier this year, according to a report Tuesday from Moscow’s state-run news service Tass.

The South Korean, identified as Baek Won-soon, was detained in Vladivostok on Russia’s eastern coast earlier this year and in February moved to a prison in Moscow, where his detention was extended until June 15, Tass reported, citing an unnamed law enforcement source.

Baek is alleged to have leaked information deemed “top secret” to foreign intelligence agencies, according to Tass.

South Korea has been “providing consular assistance as soon as it became aware of the arrest,” a Ministry of Foreign Affairs spokeswoman told Stars and Stripes by phone Tuesday.

No additional information was provided; South Korean officials regularly speak to the media on a customary condition of anonymity.

The government “expects our people to return safely ... as soon as possible” and declined to elaborate, citing the safety of the individual in custody, Foreign Affairs Ministry spokesman Lim Soo-suk during a news conference in Seoul on Tuesday.

Baek was a missionary assisting North Korean loggers working in Vladivostok, an unnamed South Korean official based in Russia said in a Chosun Ilbo report Tuesday. Baek’s wife was also arrested but later released, according to the newspaper.

Diplomatic ties between Seoul and Moscow have frayed over their respective policies on North Korea and the two-year war in Ukraine.

Since 2022, China and Russia, permanent members of the U.N. Security Council, have sided with North Korea and vetoed U.S.-sponsored resolutions to strengthen and impose new sanctions against Pyongyang.

Following Russia’s invasion of Ukraine in 2022, South Korea provided Kyiv with military supplies, such as body armor and helmets, and joined the U.S.-led effort in levying sanctions against Moscow’s exports.

South Korean President Yoon Suk Yeol in September pledged over $2.3 billion in help to Ukraine in the form of humanitarian aid and low-interest loans.

Yoon last year visited Bucha, the Ukrainian city where the U.N. Human Rights Office said it found evidence of summary executions of hundreds of civilians.

“I feel a greater responsibility as [South Korea’s] first head of state to visit Ukraine at this grave time,” Yoon said at a news conference with Ukrainian President Volodymyr Zelenskyy on July 15. “If we fight together with strong solidarity under the spirit of those seeking death shall live and those seeking life shall die, we can surely protect our freedom and democracy.”

On March 7, 2022, Moscow designated South Korea as a foreign country “involved in unfriendly activity toward Russia,” according to a Kremlin news release.

Speaking to South Korea’s sanctions during a news conference in Moscow on Dec. 27, Russian Foreign Ministry Spokeswoman Maria Zakharova said, “We reserve the right to retaliate, and not necessarily in a symmetrical way,” according to a Tass report at the time.

Russia has detained several foreigners on espionage and treason charges, including Wall Street Journal reporter Evan Gershkovich and Ksenia Karelina, a dual citizen and esthetician based in Los Angeles, according to The Associated Press.