Russia has expelled 20 employees of the Czech embassy in Moscow in retaliation for the earlier expulsion of 18 Russian diplomats from the Czech Republic, the foreign ministry in Moscow says.
According to the Czech side, the concerned people are 16 diplomats and four embassy employees without diplomatic status.
They have to leave Russia by Monday.
The Czech Republic on Saturday expelled 18 Russian diplomats because of accusations that the Russian government was involved in explosions at an ammunition depot in 2014.
The Russians have been identified as members of their country's SWR and GRU intelligence services, Czech Interior Minister Jan Hamacek said.
Russia rejected those claims, calling the move an "unprecedented decision".
On Sunday evening, the Czech ambassador was summoned to the foreign ministry for a 20-minute meeting, according to news agency TASS.
The measure means that only about five Czech diplomats remain in Moscow.