Russia on Tuesday demanded an apology from Poland and slammed what it called a delayed police response after ultra-nationalist rioters went on a rampage outside the Russian embassy in Warsaw.
The Russian foreign ministry in Moscow summoned the Polish ambassador Wojciech Zajaczkowski over Monday's unrest, during which rioters set two cars alight and overturned a guard's booth outside the Russian embassy.
"We told Zajaczkowski that we demand an official apology from the Polish authorities," the foreign ministry said in a statement, complaining that the riot had caused damage to the embassy's property and interrupted its work for several hours.
It criticized the "passivity and delayed actions of the police, which to a great extent made this riot by rowdy thugs possible."
Russia also called for the "punishment of the guilty and for such provocations not to be allowed to happen in the future."
Zajaczkowski did not make any comment on leaving the foreign ministry, Russian news agencies reported.
Around 50,000 people surged through Warsaw on Monday in a march organized by far-right groups on Poland's independence day, many wearing balaclavas and carrying lighted flares.
Four police officers were hospitalized after demonstrators threw stones and bottles.
The spokesman for Poland's foreign ministry Marcin Wojciechowski on Monday wrote on Twitter, saying: "There is no justification for hooliganism."
Poland and Russia have a history of complicated relations marked by centuries of conflicts. The integration into the West of post-Communist Poland, an EU and NATO member, is a clear cause of concern for Moscow.