MOSCOW (AP) — Russia's most prominent opposition leader, Alexei Navalny, lost another court battle Wednesday in his effort to push back against the Kremlin's widening crackdown on him and other dissenters.

Russian news agencies reported that a court rejected the latest in a series of lawsuits that Navalny has brought against prison authorities regarding his confinement. The 46-year-old politician and activist is serving a nine-year sentence in the maximum security IK-6 prison in the Vladimir region village of Melekhovo, about 250 kilometers (155 miles) east of Moscow.

Video of a hearing showed Navalny addressing the court remotely from a small room in the prison, standing, gesturing with his hands and speaking in an animated tone to protest authorities' decision to put him in a punishment cell, in solitary confinement.

“I’m considered the worst offender and I am in solitary confinement because of systematic fabrication of ridiculous violations," Navalny told the judge in the Vladimir regional city of Kovrov.

Earlier this year, prison authorities sent Navalny to a punishment cell for five days for calling an officer by his name, and again for seven days for walking three seconds in that cell without keeping his hands behind his back, in violation of prison rules. In Wednesday's hearing, Navalny complained about unfair treatment.

“There are people in cell-type rooms, but there is no one in a punishment cell but me. In fact, any convicted person should be placed in a punishment cell, because there are not more imaginable insignificant violations than one called ‘two seconds (without) hands behind back,’” Navalny said.

Navalny was arrested in January 2021 upon returning from Germany, where he had been recuperating from nerve-agent poisoning he blamed on the Kremlin. He received a 2½-year sentence for allegedly violating the conditions of his parole while outside Russia.

In March, Navalny was sentenced to nine years in prison on charges of fraud and contempt of court, allegations he rejected as a politically motivated attempt by Russian authorities to keep him behind bars for as long as possible.

Navalny’s close associates have faced criminal charges and many have left Russia. Russian authorities shut down his group’s political infrastructure — an anti-corruption foundation and a nationwide network of offices — by labeling it as an extremist organization.