Russian authorities designated the independent news outlet Meduza an "undesirable organization" on Thursday, effectively outlawing the site from operating in Russia and banning any Russian from cooperating with Meduza or its journalists.
The designation is the latest in a yearslong campaign by the Kremlin to curb independent media and stop their reporting from reaching ordinary Russians in a crackdown that has escalated since Russia invaded Ukraine last year.
In a statement announcing the decision, Russia's General Prosecutor said the Latvia-based news outlet "poses a threat to the foundations of the constitutional system and the security of the Russian Federation."
There was no immediate response from Meduza, one of Russia's most widely read independent news sites, though it did publish a news story on its website, including details about what the designation could mean.
"Undesirable organizations are banned from operating on Russian territory under threat of felony prosecution," the article, published in Russian and English, said.
"Anyone who 'participates or cooperates' with such groups can face felony prosecution — an especially serious limitation for journalists who must speak to sources to report the news," it added.
Those prosecuted for cooperating with an undesirable organization can face heavy fines or even multiyear jail terms.
More than 50 organizations are currently on the "undesirable" list, including Russian investigative news outlets iStories and Proekt, and Dutch-based Bellingcat.
The founder of Russia's private military Wagner Group, Yevgeny Prigozhin, publicly called for Meduza to be placed on the list last July.
In a letter to Russia's top prosecutor, Prigozhin attacked Meduza's reporting on the war in Ukraine. He said articles that claimed sources inside the Kremlin wanted to remove Putin from power, and that a second attack on the Ukrainian capital, Kyiv, was being planned, violated Russia's strict censorship laws.
Shortly after invading Ukraine, Russia's parliament passed legislation outlining jail terms of up to five years for "discrediting" the armed forces and up to 15 years for spreading "deliberately false information" about them.
Another independent news site, Mediazona, said on Thursday its publisher, Pyotr Verzilov, had been accused of spreading "fakes" about the army, motivated by political hatred.
Upon passing the laws last March, Russian authorities moved swiftly to block access to dozens of websites — including Meduza's — and dozens of Russian and international news outlets left the country.
Meduza has been based in Latvia since it was established in 2014. Its placement on the "undesirable" list was condemned by opposition figures on social media.
"The undesirable organization is the handful of people who have seized power in Russia," tweeted Ruslan Shaveddinov, an ally of jailed opposition politician Alexei Navalny.