Tensions between Moscow and Prague spiralled Sunday with Russia ordering out 20 diplomats, a day after the Czech Republic accused the suspects in the Skripal poisoning of being behind a deadly 2014 explosion on its soil.
Czech authorities on Saturday announced they were expelling 18 Russian diplomats identified as secret agents of the Russian SVR and GRU security services and suspected of involvement in the blast at a military ammunition warehouse that killed two people.
Police meanwhile said they were seeking two Russians in connection with the explosion and said the pair carried passports used by suspects in the poisoning of former Russian double agent Sergei Skripal in Britain in 2018.
The two Russians were identified as Alexander Mishkin and Anatoly Chepigov based on video footage from the site and photos published after the Skripal attack, according to Czech media.
But Russia on Sunday called the claims "absurd", and retaliated with an announcement that 20 employees of the Czech embassy in Moscow had been declared "persona non grata" and must leave the country by the end of Monday.
Russia announced the retaliatory measures against a background of a new spike in tensions between Moscow and the West over a litany of issues including Russia's troop build-up on Ukraine's border, interference in US elections and other perceived hostile activities.
The expulsions were unveiled after the Czech ambassador in Moscow, Vitezslav Pivonka, was summoned by the Russian foreign ministry.
"Pivonka had been told that 20 employees of the Czech embassy in Moscow had been declared 'persona non grata'," the foreign ministry said in a statement.
- 'Almost an act of war' -
"They have been ordered to leave our country by the end of April 19, 2021," the ministry added, calling the Czech government's decision to expel Russian diplomats "unprecedented" and a "hostile act".
"In their desire to please the United States against the background of recent US sanctions against Russia, Czech authorities in this respect even outdid their masters from across the pond," the ministry said earlier Sunday.
This week the United States announced sanctions and the expulsion of 10 Russian diplomats in retaliation for what Washington said was the Kremlin's US election interference, a massive cyber attack and other activity.
In Prague, protesters on Sunday smeared the Russian embassy wall with ketchup and politicians vowed consequences.
"Killing the citizens of the Czech Republic on its territory by another country, that's almost an act of war," protester Tomas Peszynski told AFP at a rally outside the Russian embassy in Prague.
Around 100 protesters sported banners saying "We're not Russia's backyard" and chanted "Shame" while waving EU and NATO flags.
The night before, police detained seven people who had smeared the embassy wall with ketchup.
Czech politicians joined the outcry, with government ministers saying Russian companies should not take part in the planned construction of a new nuclear unit worth billions of euros for security reasons.
"I can't imagine (Russian energy giant) Rosatom getting as far as the security assessment," Industry Minister Karel Havlicek said.