The Moscow City Court started considering merits of the espionage case of Ukrainian citizen Roman Sushchenko on Tuesday.

"Sushchenko pleaded not guilty after the bill of indictment was read out," lawyer Mark Feygin told Interfax.

The court meets in private because some materials in the proceeding are classified, he said.

Sushchenko is accused of spying. He is facing up to 20 years in prison.

On October 3, 2016, it was reported that Sushchenko had been detained "while conducting espionage" in Moscow. According to Russian intelligence agencies, Sushchenko is a career officer of the Main Intelligence Directorate of Ukraine's Defense Ministry with the rank of colonel. Sushchenko is charged with espionage (article 276 of the criminal code), which he denies.

Feygin said his client was charged with several instances of espionage. The FSB believes that Sushchenko was collecting information about the conflict in Donbas.

The lawyer said that Sushchenko, who lived in France for six years as the Paris correspondent of the news agency Ukrinform, repeatedly visited Russia. He was in Russia for personal reasons; a meeting with his family, when he was detained.

Kyiv described Sushchenko's detention as a provocation and said that the espionage accusations were false.