A court in Moscow has prolonged the pretrial detention for a Russian citizen charged with high treason and espionage for the United States.

Yevgeny Petrin's lawyer, Ivan Pavlov, told the TASS news agency on February 3 that the Moscow City Court had prolonged his client's pretrial detention until March 5.

The case against Petrin, who was arrested in January 2015, is classified.

Petrin's lawyers said earlier that their client had pleaded not guilty.

Petrin's relatives have said Petrin used to work for Russia's Federal Security Service (FSB) and quit the agency in 2013.

Reports have said that Petrin was an employee of the Moscow Orthodox Patriarchate's department for external ties and worked in the Ukrainian capital, Kyiv.

Based on reporting by TASS