MOSCOW (Reuters) - U.S. government-sponsored Radio Free Europe/Radio Liberty (RFE/RL) said on Monday Moscow had threatened to brand their Russian language service projects as “foreign agents” in retaliation for what Moscow calls U.S. pressure on a Kremlin-backed TV station.

Russian officials have accused Washington of putting unwarranted pressure on the U.S. operations of RT, a Kremlin-funded broadcaster accused by some in Washington of interfering in domestic U.S. politics, which it denies..

Russian Foreign Ministry spokeswoman Maria Zakharova said on Sunday Moscow could apply “similar measures” to American journalists and media in Russia. She did not identify any specific U.S. media outlets that would be targeted.

Current Time, which is produced by RFE/RL in cooperation with the Voice of America and mainly targets audiences in Russia and the countries of Central and Eastern Europe, said it had received a warning from the Russian Ministry of Justice, threatening to put restrictions on the network.

Two other RFE/RL Russian-language projects, Radio Liberty and Idel. Realias, received the same letters, it said.

“According to Russia’s competent bodies, your organization’s activity falls under the criteria set out in the federal law... for non-commercial organizations - foreign agents. Your organization’s activity may be restricted...,” said the letter, seen by Reuters.

A justice ministry official confirmed to Reuters that such a letter had been sent, adding: “The principle of reciprocity will further be applied depending on the measures applied to Russian media by the United States.”

Responding to the letter, the channel director of Current Time TV, Daisy Sindelar, said in a statement: “We are a journalistic organization, and we trust we will be able to continue our work.”

“We have no concrete information about any moves being taken against RT in the United States, and have no reason to expect reciprocal action”, she added.

Late last month, Russia’s state communications regulator accused U.S. TV channel CNN International of violating its license to broadcast in Russia and said it had summoned the broadcaster’s representatives in connection with the matter.