Russian President Vladimir Putin has signed legislation that empowers the government to designate media outlets receiving funding from abroad as "foreign agents" and impose sanctions against them.

The new law was published on Russia's official legal information Internet portal on Saturday.

The measure passed the Federation Council, the upper chamber of parliament, Wednesday in a unanimous 154-0 vote, with one abstention.

And it was unanimously approved in the third and final reading in the lower house, the State Duma, on November 15. Within hours, the Justice Ministry sent warnings to several Radio Free Europe/Radio Liberty (RFE/RL) news services.

The letters did not specify what potential restrictions they could face, but lawmakers have said designated media could be subjected to detailed financial-reporting requirements and required to label published material as coming from a foreign agent.

RFE/RL was among several media outlets that Russian officials warned could be labeled a foreign agent, a list that also included the Voice of America (VOA), CNN, and Germany's international broadcaster, Deutsche Welle.

In response to news that Putin signed the law, RFE/RL President Thomas Kent said, "We cannot speculate at this time on the effect of the new law, since no news organization has yet been specifically named as a 'foreign agent' and the restrictions to be imposed on such 'agents' have not been announced."

"We remain committed to continuing our journalistic work, in the interests of providing accurate and objective news to our Russian-speaking audiences," he added.

John Lansing, director of the Broadcasting Board of Governors which oversees VOA and RFE/RL, said in a statement Saturday, "RFE/RL, VOA, and the other networks of U.S. international media will remain committed to our mission, stipulated by U.S. law, to provide accurate, objective, and comprehensive journalism and other content to our global audiences, including in the Russian Federation.

"We will study carefully all communications we may receive from Russian authorities concerning our operations. While we will not speculate as to the effect that any new steps by the Russian government will have on our journalistic work, any characterization of such steps as reciprocity for U.S. actions severely distorts reality," Lansing said.

The international rights organization Amnesty International has said the legislation would deal a "serious blow" to media freedom in Russia, although Russian officials have said it would not apply to domestic media.

Russian officials have called the new legislation a "symmetrical response" to what they describe as U.S. pressure on Russian media. On November 13, the Russian state-funded television channel RT registered in the United States under a decades-old law called the Foreign Agents Registration Act.

Lansing, however, denied Moscow's actions were "symmetrical." "Russian media, including RT and Sputnik, are free to operate in the United States and can be, and are, carried by U.S. cable television outlets and FM radio stations. However, U.S international media, including VOA and RFE/RL, are banned from television and radio in Russia," he said in a statement released Saturday.

The U.S. Justice Department required RT to register in the wake of a January finding by U.S. intelligence agencies that RT and Russia's Sputnik news agency spread disinformation as part of a Russian-government effort to influence the 2016 U.S. presidential election.

In a November 15 statement, RFE/RL said the "situation regarding Russian media in the U.S. and U.S. media in Russia remains vastly unequal."

"RT and Sputnik distribute freely in the U.S., whereas RFE/RL has lost its broadcast affiliates in Russia due to administrative pressures, and has no access to cable," it said. "RFE/RL reporters are subject to harassment and even physical attack in Russia."

Visiting the Moscow bureau of RFE/RL and VOA on November 17, U.S. Ambassador Jon Huntsman said that the Russian legislation was a "big concern" for the United States and that "the principles of free media in any free society and democracy are absolutely critical for strength and well-being."