MOSCOW: Russian investigators have charged a scientist specialising in the Arctic region with treason, his lawyer said on Monday, accusing him of handing state secrets to China.

Valery Mitko, the 78-year-old president of the Saint Petersburg-based Arctic Academy of Sciences, has been under house arrest since his indictment in February, his lawyer Ivan Pavlov said, although news of his detention only recently emerged.

Mitko is accused by the FSB security service of passing classified information to Beijing during frequent trips to China where he gives lectures, Pavlov said. The lawyer said Mitko was ordered to remain under house arrest until October.

The scientist faces up to 20 years in prison if he is found guilty of treason. He insists he is innocent.

A spokesperson for the Dzerzhinsky court in Saint Petersburg confirmed to AFP that Mitko was being held under house arrest, but declined to give details of the case, saying it was classified.

Pavlov said his client only travelled to China with documents relating to his research and lectures. Investigators have not specified what information they believe Mitko passed to China, his lawyer said.

Sources told Russian news agencies TASS and Interfax that the scientist passed information on the detection of submarines. Several researchers have previously been convicted of treason or espionage in cases that stirred controversy.