MOSCOW (Reuters) -A Russian court on Tuesday rejected an appeal by a South Korean citizen held on charges of espionage against the extension of his pre-trial detention, ruling to keep him in custody until at least Nov. 15, the RIA state news agency reported.
Russian authorities detained the man, Baek Won-soon, in March in the far eastern city of Vladivostok before transferring him to Moscow for "investigative actions", the TASS state news agency reported at the time.
Relations between Russia and South Korea have become increasingly strained as Moscow builds up ties with communist North Korea.
TASS said the espionage case was the first involving a South Korean national. If found guilty, Baek faces up to 20 years in prison.
His lawyer, Dmitry Ivanov, told RIA on Tuesday he could not disclose details of the case due to its sensitivity, but said his client denied any wrongdoing.
In March, the leader of a South Korean aid group described Baek as a missionary and head of its operations in Vladivostok, saying the accusations of espionage were "totally absurd" and "completely untrue".
The South Korean foreign ministry could not be reached for comment outside of working hours on Tuesday. Seoul has previously said it is communicating with Moscow to try to secure Baek's release.
Ivanov, Baek's lawyer, told RIA on Tuesday that his client, who is being held in the Lefortovo pre-trial detention centre in Moscow, was suffering from health problems.
Ivanov told RIA that South Korean embassy officials visited Baek once a month and that his client was given medicine.