The wife of a South Korean missionary detained in Russia on espionage charges has reportedly begun the process to appoint a lawyer in preparation for legal proceedings.

According to local sources on Thursday, the wife of the detainee, identified by his surname Baek, has sought assistance from the South Korean Embassy in Moscow regarding the appointment of legal counsel.

A source said Baek's wife is in regular communication with the embassy to inquire about her husband's case and response measures, adding that while she could travel to Russia to appoint a lawyer herself, the embassy is able to do so on her behalf.

Earlier this week, the embassy requested for Russia's Federal Security Service to permit a consular visit with Baek to check for any violations of human rights and to assess the state of his health.

Baek, who had been working as a missionary in Russia's Far East for nearly a decade, was detained in Vladivostok in January on espionage charges. He is reportedly being held in Lefortovo Prison in Moscow.