Russia's denial of entry of a South Korean national and its subsequent decision to impose a 30-year entry ban on the person appears to be unrelated to the bilateral relations that have soured amid Moscow's war in Ukraine, a Seoul official said Thursday.

Lim Soo-suk, the foreign ministry spokesperson, made the comment after the Donga Ilbo daily reported that a South Korean businesswoman, who has spent more than 20 years doing business in Russia, was denied entry last month upon arrival and issued an entry ban for 30 years until 2054.

The unidentified woman in her 60s claimed that the Russian authorities only cited "state secrets" as the reason for her denial of entry. She also said that the entry ban came after the Russian immigration authorities turned down her bid to gain permanent residency.

"We are aware of the case. We do not think that this case has much to do with the South Korea-Russia relations," Lim said during a press briefing. He declined to provide further details, citing privacy concerns.

The latest case draws attention as the bilateral ties between Seoul and Moscow have remained frosty since South Korea joined the U.S.-led move to impose sanctions against Russia over its invasion of Ukraine.

Russia has labeled South Korea as one of the unfriendly nations, calling for the withdrawal of a string of economic sanctions Seoul has imposed on Moscow.

Russia revealed early last month that a South Korean missionary, identified only by his family name Baek, has been held in the Lefortovo detention facility in Moscow since late February on espionage charges, a claim denied by the Christian aid group he works for.

The foreign ministry in Seoul said it is communicating with the Russian side over Baek's arrest and taking steps to provide necessary consular assistance. (Yonhap)