A pair of Russian journalists have been detained on “extremism” charges and face accusations of working for a group founded by the late Russian opposition politician Alexey Navalny.

Konstantin Gabov and Sergey Karelin are accused of producing content for Navalny’s prominent YouTube channel, “NavalnyLIVE,” which publishes videos investigating corruption in the Kremlin that have amassed millions of views.

Russian authorities have designated Navalny, who died in an Arctic prison in February, and his organizations as “extremist.” Members of his team have previously been imprisoned and many live in exile.

Gabov was allegedly involved in the “preparation of photo and video materials” for the YouTube channel, Moscow’s Basmanny District Court press service said. He was arrested Saturday and will remain in detention until June 27.

Karelin was arrested in Russia’s northwest Murmansk region on Saturday and is accused of “participation in an extremist organization.” He previously worked for a number of outlets including the Associated Press (AP) and German publication Deutsche Welle (DW), until DW was banned in Russia in 2022.

An AP photo showed Karelin, who has dual Russian-Israeli citizenship, sitting in a glass cage in a Murmansk court on Saturday.

The pair’s detention comes amid a heightened crackdown in Russia on journalists and Kremlin critics, as President Vladimir Putin has sought to stifle dissent more fiercely than before the invasion of Ukraine.

Forbes journalist Sergey Mingazov was also placed under house arrest Saturday after he was detained for allegedly spreading fake news about the Russian army, state media RIA Novosti reported.

Navalny was Putin’s most formidable political opponent before his death in a penal colony, where he was serving a more-than-30-year sentence on extremism charges. Navalny’s family and supporters have accused Putin of being responsible for his death, a claim rejected by the Kremlin.