Russian authorities have restricted access to the website of imprisoned opposition leader Alexei Navalny and to dozens of sites run by his close allies, Navalny’s team said Monday.

The action came amid mounting government pressure on opposition supporters, independent journalists and human rights activists in Russia ahead of the country’s parliamentary election. The September vote is widely seen as an important part of President Vladimir Putin’s efforts to cement his rule before a 2024 presidential election.

The 68-year-old Russian leader, who has been in power for more than two decades, pushed through constitutional changes last year that would potentially allow him to hold onto power until 2036.

Navalny’s website, as well as the website of his top strategist, Leonid Volkov, and longtime ally Lyubov Sobol were unavailable on Monday. The websites of Navalny’s Foundation for Fighting Corruption and a network of about 40 regional offices, which the Russian government outlawed as extremist groups last month, also could not be accessed; neither could the website of the Navalny-backed Alliance of Doctors union and an online page calling for Navalny’s freedom.

According to Russia’s state communications watchdog, Roskomnadzor, access to all of the websites was restricted at the behest of the Russian prosecutor general’s office. In a statement to the Interfax news agency, Roskomnadzor confirmed blocking the websites, saying they were being “used for propaganda” of extremist groups.

“(They) have decided to completely wipe us out of the internet,” Navalny associate Maria Pevchikh tweeted.

Navalny, who is Putin’s most ardent political foe, was arrested in January upon returning from Germany, where he spent five months recovering from a nerve agent poisoning that he blames on the Kremlin — an accusation that Russian officials reject.

In February, Navalny was ordered to serve 2 1/2 years in prison for violating the terms of a suspended sentence from a 2014 embezzlement conviction that he dismissed as politically motivated.

His arrest and jailing sparked a wave of mass protests across Russia’s 11 time zones, in what appeared to be a major challenge to the Kremlin. The authorities responded with mass arrests of demonstrators and the criminal prosecutions of Navalny’s closest associates.

The politician’s Foundation for Fighting Corruption, which he launched founded 10 years ago and has published dozens of colorful and widely watched videos exposing the alleged corruption senior government, was labeled as an extremist group along with the network of regional offices Navalny had relied on to organize protests.

The ruling not only barred the foundation and the offices from operating, but also prevents people associated with the organizations from seeking public office and exposes them to lengthy prison terms.

Navalny’s team pointed out Monday that the website of Smart Voting – a project to support candidates most likely to defeat the ones from the Kremlin’s dominant United Russia party in various elections – remained available.

Strategist Volkov suggested that authorities might block the strategy site “closer to the election” in September, in which Navalny’s team plans to deploy the Smart Voting project.

Ivan Zhdanov, a close Navalny ally, said in an Instagram post that the politician’s team was “was not surprised” by the website blocks “and therefore ready” for them. Zhdanov urged supporters to follow Navalny’s team and its members on social media, “where it’s harder to block us,” and to download a mobile app that contains all the recent investigations and the Smart Voting project.

“An app cannot currently be blocked,” Zhdanov wrote.

(AP)