Russia's media watchdog on Wednesday warned U.S.-funded Radio Free Europe/Radio Liberty it had 60 days to pay more than $70,000 in fines over non-compliance with its "foreign agent" law.
The statement came after U.S. Secretary of State Antony Blinken on Tuesday expressed support for RFE/RL and other U.S. international media.
Moscow had imposed "invasive labelling requirements and fines" to "drive RFE/RL out of Russia," said a State Department statement.
Groups or individuals identified as "foreign agents" in Russia must disclose their sources of funding and label publications with the relevant tag or face fines.
State media regulator Roskomnadzor said it had drawn up a total of 390 protocols against RFE/RL — ruled a foreign agent in 2017 — and its director for failing to label nine of its websites operating in Russia.
Jamie Fly, the president of RFE/RL, denounced the fines as "illegitimate" and said they were aimed at muzzling the broadcaster.
"RFE/RL is being targeted by the Russian authorities because we continue to provide a growing audience in Russia with objective news and information at a moment when the Kremlin is trying to limit the Russian people's access to information," Fly said in a statement in response to AFP.
"We will not abandon our audience no matter how many illegitimate fines the Russian authorities impose on us," he added. "We will continue to fight these attacks on our journalistic independence through all possible means."
A Russian court had ordered the broadcaster to pay 71.5 million rubles ($925,000) in fines after considering 260 of the protocols.
RFE/RL appealed, but Moscow's Tverskoi district court on Wednesday rejected the appeal, ordering it to pay 5.5 million rubles ($71,000) worth of the fines within 60 days.
Last month, Reporters Without Borders described the penalty as "the heaviest fines ever imposed on a media outlet in Russia."
The media rights watchdog added: "The absurd law requiring this self-labelling violates media pluralism and is designed to silence independent and opposition media."
Legislation allowing authorities to brand organizations with the term "foreign agent" was originally passed in 2012 to cover NGOs.
It was expanded to include media organizations in 2017 after Kremlin-funded RT (formerly Russia Today) was declared a foreign agent in the United States.