The Czech foreign ministry summoned Russia's ambassador Friday amid a row over a controversial Soviet-era statue in Prague that city authorities want to replace with a World War II memorial.
Prague authorities put a tarp over the vandalised statue of Soviet General Ivan Konev in August, triggering a sharp reaction from Moscow.
Russian Culture Minister Vladimir Medinsky called Ondrej Kolar, mayor of Prague's sixth district who approved the tarp, a "gauleiter", or a regional Nazi Party leader during World War II.
Medinsky also accused Kolar of supporting hooligans and tarnishing the memory of Soviet soldiers.
On Friday, the Russian foreign ministry said it was "appalled by the cynical decision of the municipal authorities" to move the statue.
The decision will become "an irritant in bilateral relations, seriously darken their atmosphere and will not go unanswered," the ministry said in a statement.
While Konev is regarded as a hero in Russia, many Czechs see him as a symbol of Soviet-era oppression.
He led Red Army troops that liberated Prague from the Nazis in 1945, but he was also in charge of Operation Whirlwind, which crushed the anti-Soviet Hungarian Uprising of 1956.
Konev, who died in 1973, also played a role in the 1968 Soviet-led crackdown on the Prague Spring, a democratic movement in then-Czechoslovakia.
Czech deputy foreign minister Ales Chmelar on Friday "summoned Russian Federation ambassador Alexander Zmeyevsky to protest against untrue and insulting statements of a Russian minister aimed at the Prague (district) six mayor," the foreign ministry said in a statement.
On August 21, the anniversary of the 1968 invasion of Czechoslovakia, someone sprayed "No to the blood-covered marshal, we shall not forget" on Konev's brass statue that was erected by the then communist regime in 1980.
City hall then covered up the statue, but pro-Konev protesters tore down the tarp and held a rally in its support.
It was attended by several lawmakers with Russian sympathies and Jiri Ovcacek, the spokesman for pro-Russian, pro-Chinese Czech President Milos Zeman.
Prague authorities decided Thursday to replace Konev's statue with a memorial of the liberation of the capital during WWII.
Konev's daughter told Czech media his statue could be moved to Russia.