Former U.S. Marine Paul Whelan, who is charged with espionage against Russia, is seen on a screen via a video link during a court hearing in Moscow, Russia, November 19, 2019. REUTERS

Moscow — A Russian court has rejected a former U.S. Marine's latest appeal to end his detention on espionage charges. The Moscow court rejected Paul Whelan's appeal Tuesday against a move to extend his detention.

Whelan, 49, was arrested in Moscow last December at the Metropol Hotel, allegedly in possession of a USB drive containing classified information. He insists he was set up by Russia's Federal Security Service and has repeatedly called the case against him politically motivated.

Whelan was not allowed to attend the Tuesday hearing in person as the Moscow City Court considered his latest appeal against being held in custody. He participated via a video link from Russia's notorious Lefortovo prison.

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His detention has already been extended until December 29. Whelan's defense team said they petitioned for him to be present in court, but the judge ruled that it was best for him not to be transported, citing health concerns. The American has been suffering from an apparent hernia.

When reporters entered the courtroom on Tuesday the sound on Whelan's video feed was switched off, denying him the chance to make statements to the gathered press as he's done during previous appearances. Monitors showed him sitting behind bars holding up a piece of paper with a written statement, but it was unreadable due to poor video quality.

The prisoner was also denied real-time translation of Tuesday's court proceedings. With the audio on his feed switched on later, he could be heard saying, "I have no idea what is happening." The court said he would receive a full translation later.

Whelan's defense team said they were planning to appeal again against his ongoing detention.

Independent Russian newspaper Kommersant published what it said were leaked details of the charges against the American over the weekend. The paper said he had been on the Federal Security Service's (FSB) radar since 2007, when he visited the country for the first time while still serving in the Marines.

The report, citing anonymous sources, said the U.S. resident drew the spy agency's attention because he tried to contact former and serving members of the Russian military and the FSB. Russian officials have said he received the USB drive from a serving FSB employee, and that it contained a classified staff list for one of the agency's departments.

"We think it was a provocation by his acquaintance," defense lawyer Vladimir Zherebenkov said on Tuesday. "None of the witnesses questioned have testified that Paul tried to recruit him."

Whelan's family insists he came to Russia to attend a friend's wedding, and that he believed the USB drive handed to him by an acquaintance contained vacation photos.

Whelan, a Michigan resident who also holds British, Canadian and Irish citizenship, faces up to 20 years in prison if convicted of espionage.

Analysts have suggested Russia could try to use Whelan as a bargaining chip in negotiating a prisoner swap for Russian nationals detained abroad. His lawyer on Tuesday appeared to call for such negotiations to begin promptly.

"Paul is a citizen of four countries. None of them has asked to organize his exchange yet. Take the initiative, gentlemen!"

said Zherebenkov.

Hearings in Whelan's case are not expected to begin until at least March.