(Adds Kremlin comments)
MOSCOW, Sept 29 (Reuters) - Russia's communications regulator on Friday accused U.S. TV channel CNN International of violating Russian media law and said it had summoned the broadcaster's representatives in connection with the matter.
The Russian foreign ministry accused Washington on Thursday of putting unwarranted pressure on the U.S operations of Kremlin-backed media outlet RT, and warned that Moscow could take tit-for-tat measures.
President Vladimir Putin told a meeting of Russia's Security Council on Friday that Russian media outlets working abroad were facing growing and unacceptable pressure, his spokesman Dmitry Peskov said.
The communications regulator, Roskomnadzor, said in a statement on its website that it would look at warning CNN about the alleged violations, which it said also breached the terms of its broadcast licence.
It did not say what breaches of Russian laws the U.S. broadcaster had made, adding it would continue its "systematic monitoring" of foreign mass media outlets registered in Russia.
Asked if the regulator's move was politically motivated, Roskomnadzor head Alexander Zharov, was quoted by Interfax news agency as saying: "I don't work in a political agency. I work in a regulatory service."
Russian Foreign Ministry spokeswoman Maria Zakharova said on Thursday the U.S. authorities were demanding that Russian state-controlled broadcaster Russia Today (RT) be registered as a "foreign agent" in the United States.
She said that move endangered the safety of the channel's staff, because it included an obligation to disclose their personal data. "In the atmosphere of a witch hunt unfolding in the United States, this may present a real threat," she said.
Putin, meeting permanent members of his Security Council, "touched upon the issue of ongoing and at times growing pressure on Russian mass media outlets in some foreign countries", Peskov told a conference call with reporters.
"It was stressed that such pressure on Russian media is unacceptable," he added. He did not name the countries where the Kremlin was concerned Russian media were coming under pressure.
The Foreign Ministry's Zakharova said any move made against Russian media working in the United States "will get a tit-for-tat response".
"And who it falls on, this should be easy for Washington to work out. The clock is ticking," she said at a weekly briefing on Thursday. (Reporting by Vladimir Soldatkin and Dmitry Solovyov,; Editing by Christian Lowe and Ed Osmond)