Authorities in Russia have declared dozens of news outlets, think tanks and non-profit organisations "undesirable" since 2015, a label rights groups say is designed to deter dissent.

In a statement, Russia's Prosecutor General accused SOTA of "frank attempts to destabilise the socio-political situation in Russia" and "create tension and irritation in society".

"Such activities, obviously encouraged by so-called Western inspirers, have the goal of undermining the spiritual and moral foundations of Russian society," it said.

It also accused SOTA of co-operating with TV Rain and The Insider, two other independent Russian-language outlets based outside of the country that are linked to the opposition.

SOTA Project, which covers opposition protests and has been fiercely critical of the Kremlin, denied it had anything to do with TV Rain and The Insider and rejected the claims.

But it advised its followers in Russia to "remove reposts and links" to its materials to avoid the risk of prosecution. SOTA's Telegram channel has around 137,000 subscribers.

"Law enforcement and courts consider publishing online to be a continuing offence. This means that you can be prosecuted for reposts from 2023, 2022, 2021," it said.

SOTA Project was born out of a split with a separate news outlet called SOTAvision, which still covers the opposition but distanced itself from the prosecutors' ruling on Thursday.

Since launching its offensive in Ukraine, Moscow has waged an unprecedented crackdown on dissent that rights groups have likened to Soviet-era mass repression.

Among other organisations labelled as "undesirable" in Russia are the World Wildlife Fund, Greenpeace, Transparency International and Radio Free Europe/Radio Liberty.