A Russian court on Friday sentenced three lawyers for the late opposition leader Alexei A. Navalny to up to five and a half years in prison for passing his correspondence to his allies, a stark reminder that the Kremlin is still pursuing his associates even after his death.

Three lawyers — Vadim Kobzev, Igor Sergunin and Aleksej Liptser — were arrested in October 2023, while Mr. Navalny was in a high-security prison colony in Siberia, in a stark warning that the Kremlin intended to sever ties with Mr. Navalnyja with the outside world.

A city court in Petushka, about 80 miles east of Moscow, convicted three lawyers, all of whom represented Mr. Navalny at some point in the past decade, of involvement in the extremist group, Russian news agencies reported from the courtroom.

Even from prison, Mr. Navalny has been the most popular opposition figure in Russia, defiantly challenging the rule of President Vladimir V. Putin, and authorities banned his national movement as extremist shortly before the 2022 invasion of Ukraine.

Mr. Kobzev was sentenced to five and a half years in prison, Mr. Liptser to five years, and Igor Sergunin, the only one of the three who pleaded guilty, to three and a half years.

Julija Navalnaja, widow of Mr. Navalny, ua statement on Friday, he called the three lawyers political prisoners and demanded their release. And Lyubov Sobol, one of Mr. Navalny’s longtime allies, he said on X that the verdict was “dictated by the Kremlin and that it wants to take revenge on those who remained on Navalny’s side until the end”.

Prosecutors said during the trial that the lawyers “used their position” to pass Mr. Navalny’s correspondence from the Petushka prison colony, where he spent time before being transferred to Siberia, to his allies in Russia and abroad.

In its ruling, the court agreed with their claim that this allowed Mr. Navalny “to carry out his role as the leader and head of an extremist organization.”

Two other lawyers Mr. Navalny, Olga Mikhailova and Alexandr Fedulov were charged in absentia because they fled the country. Their case has yet to be heard.

Mr Navalny was serving a 19-year sentence on several charges when he died in a high-security prison colony in February last year. Russian authorities attributed his death to a series of illnesses exacerbated by a heart arrhythmia, a conclusion strongly rejected by his family and allies, with Ms Navalnaya suggesting the state was responsible for his death.

Some of the letters and prison diaries that the lawyers helped to get out of Petuški prison are included in Mr. Navalny memoirswhich was published posthumously at the end of last year.

Lawyers Mr. Navaljno claimed at the trial that they were prosecuted for routine legal work, such as liaising between a client and their family or co-workers.

Mr. Kobzev, who worked side by side with the opposition leader, told the court that “we are being tried for communicating Navalny’s thoughts to other people,” according to the Novaya Gazeta newspaper.

The three lawyers were placed in a cage in the courtroom, and at the beginning of the hearing on Friday, fans chanted “We are proud of you! You are the best people of Russia!” as they smiled at fans and journalists, according to social media footage.

In an apparent attempt to soften the show of support, the police detained four journalists and one fan on Friday morning as they arrived in Petuški by train. They were released without charge after the announcement of the verdict, according to Mediazona, an independent media outlet in Russia.

The prosecution of the lawyer was in line with the Kremlin’s attempt to isolate Mr. Navalny, who managed to remain an important voice in Russian politics despite his imprisonment, and his Anti-Corruption Foundation.

The lawyers who represented their three colleagues told reporters outside the court that the prosecution did not intimidate them. “Things can be different, but being a lawyer does not mean being afraid,” said one of them, Denis Leisle, who represents Mr. Liptser, in an interview with Mediazona.

Ivan Zhdanov, president of the Anti-Corruption Foundation, said the ruling would set a dangerous precedent for the country’s legal system, as people could be held responsible for something as innocuous as forwarding correspondence.

“The lawyers already knew they were being monitored during meetings with their clients,” he wrote on his Telegram channel. “Now they will know that they were being followed, filmed and that could be used against them in court to convict them.”