MOSCOW:A Russian court is due to consider jailing Kremlin critic Alexei Navalny for up to three and a half years later on Tuesday in a case that has sparked nationwide protests and talk of new Western sanctions.

Navalny, one of President Vladimir Putin's most prominent critics, was arrested at the Russian border on Jan. 17 after returning from Germany where he had been recovering from a nerve agent poisoning in Russia.

Navalny accuses Putin of ordering his murder, something the Kremlin denies. It in turn has suggested that Navalny is an asset of America's Central Intelligence Agency, a charge he rejects.

Moscow's state prison authority accuses Navalny of parole violations and wants the court to convert a suspended sentence he had been serving in an embezzlement case he calls trumped up into a real jail term of up to three and a half years.

Navalny says he was unable to report into the prison service at the end of last year because he was recovering in Germany from being poisoned.

State prosecutors said on Monday that they would ask the court to grant the prison authority's request.

Navalny is already serving out a 30 day detention sentence in connection with the same case.

Navalny's supporters have staged two straight weekends of nationwide protests demanding he be freed, despite a massive show of police force, the threat of arrest, bitter cold and the pandemic.

Navalny's political allies have appealed to his supporters to gather outside the court on Tuesday to support him, an action the authorities would regard as an illegal protest.

Riot police were deployed in large numbers near the court ahead of the hearing that was expected to begin at 0800 GMT.