MOSCOW, March 21. /TASS/. The Russian Foreign Ministry on Monday summoned US Ambassador to Russia John Sullivan and issued a demarche and a note of protest to him over the recent "unacceptable" remarks by President Joe Biden regarding Russian President Vladimir Putin.

"On March 21, US Ambassador John Sullivan was summoned to the Russian Foreign Ministry where he was issued a demarche and handed a note of protest in connection with the recent unacceptable remarks by the head of the White House Joe Biden regarding the president of Russia," the ministry said in a statement.

"It was emphasized that such statements by the US president, which are unworthy of a statesman of such a high rank, bring Russian-US relations to the brink of breaking off," the statement said. "We have warned that hostile actions taken against Russia will receive a decisive and firm rebuff."

In addition, the ministry said that during a discussion of current bilateral issues the ambassador was "strongly confronted with the issue of ensuring normal working conditions for Russian diplomatic missions in the US, including guarantees for their uninterrupted functioning."

On March 17, Biden used insults and offensive language in remarks about his Russian counterpart, calling him a "murderous dictator and a pure thug who is waging an immoral war against the people of Ukraine." A day earlier, when asked by a reporter, the US president said he considered Putin a "war criminal." Kremlin Spokesman Dmitry Peskov told TASS these remarks by Biden are unacceptable and unforgivable.