The Kremlin on Monday denounced the "provocative and unfriendly" expulsion of 18 Russian diplomats from the Czech Republic who were accused by authorities in Prague of spying.
"We categorically do not agree with these conclusions," Kremlin spokesman Dmitry Peskov told reporters, describing the Czech move as "provocative and unfriendly."
Czech authorities on Saturday said they would expel the diplomats identified by local intelligence as secret agents of Russian security services who are suspected of involvement in a 2014 blast that killed two people.
Russia responded on Sunday by announcing 20 employees of the Czech Embassy in Moscow "persona non grata" and saying they had to leave the country before the end of Monday.
The expulsions were announced after the Czech ambassador in Moscow, Vitezslav Pivonka, had been summoned by the Russian Foreign Ministry.
Also on Monday, the ministry's spokeswoman Maria Zakharova said that the "hastily fabricated" accusations were aimed at distracting from "accumulated problems in EU countries and in the West in general."
"Without a doubt, it is the United States that is behind this," she said in a televised appearance.
She added that in response both the Czech and the U.S. embassies in Moscow will no longer be allowed to employ Russian citizens.