MOSCOW (AP) — Prosecutors on Tuesday asked a Moscow court to fine jailed Russian opposition leader Alexei Navalny on charges of defaming a World War II veteran, maintaining pressure on the top Kremlin foe.

Navalny rejects the accusations of slandering the veteran who was featured in a video last year promoting constitutional amendments that allowed an extension of President Vladimir Putin’s rule.

Navalny, 44, an anti-corruption investigator and Putin’s most prominent critic, was arrested last month upon returning from Germany, where he spent five months recovering from a nerve-agent poisoning that he blames on the Kremlin. Russian authorities have rejected the accusation.

Earlier this month, a Moscow court sentenced Navalny to two years and eight months in prison for violating terms of his probation while recuperating in Germany. The sentence stems from a 2014 embezzlement conviction that Navalny has rejected as fabricated and the European Court of Human Rights has ruled to be unlawful.

During Tuesday's hearings at Moscow's Babushkinsky District Court, prosecutors asked the judge to order Navalny to pay a fine of 950,000 rubles (about $13,000) for slandering the 94-year-old veteran. Navalny, who called the veteran and other people featured in last year's pro-Kremlin video “corrupt stooges,” “people without conscience” and “traitors,” rejected the slander charges and described them as part of the authorities' efforts to disparage him.

The next court session is scheduled for Saturday.

Navalny's arrest and imprisonment triggered a wave of protests across Russia. The authorities responded with a sweeping crackdown, detaining about 11,000 participants, many of whom were fined or handed jail terms ranging from seven to 15 days.

Russia has rejected Western criticism of Navalny's arrest and the crackdown on demonstrations as meddling in its internal affairs.