Three lawyers who once represented the late Russian opposition leader Alexei Navalny were jailed on Friday in Russia.

Vadim Kobzev, Igor Sergunin and Alexei Liptser were jailed from 3.5 to five years by a court in the town of Petushki, about 100 kilometres east of Moscow.

They were arrested in October 2023 on charges of involvement with extremist groups, as Navalny’s networks were deemed extremist by authorities.

The case was widely seen as a way to increase pressure on the opposition to discourage defence lawyers from taking political cases.

At the time, Navalny was serving a 19-year prison term on several criminal convictions, including extremism.

He died in a Russian prison camp in February 2024.

Navalny, an anti-corruption campaigner and outspoken opponent of President Vladimir Putin, was arrested in 2021 upon his return from Germany, where he was recuperating from a nerve agent poisoning he blamed on the Kremlin.

He was ordered to serve 2.5 years in prison.

After two more trials, his sentence was extended to 19 years.

He and his allies said the charges were politically motivated and accused the Kremlin of seeking to jail him for life.

In December 2023, Navalny was moved from a penal colony in the Vladimir region east of Moscow to one above the Arctic Circle, where he died in February at the age of 47 under still-unexplained circumstances.

His widow, Yulia Navalnaya, and members of his team alleged he was killed on orders from the Kremlin.

The Russian government has rejected the accusation. (AP)