The Kremlin hit back on Friday at calls by Polish Prime Minister Mateusz Morawiecki to "root out" Russia's "monstrous ideology".
"This is the quintessence of that hatred towards Russians that has regrettably, like a metastasis, infected the entire Polish leadership and, in many ways, Polish society," Kremlin spokesperson Dmitry Peskov told reporters in briefing.
Morawiecki had said Russian President Vladimir Putin was more dangerous than either Adolf Hitler or Josef Stalin because of the advanced weapons at his disposal, in a column for Britain's Telegraph newspaper on Tuesday.
"This shocking statement, unfortunately, is hysterical and unacceptable," Peskov said.
Relations between NATO member Poland and Russia, already tense, have sunk even lower since Russia sent troops into Ukraine, Poland's neighbour, on Feb. 24.
Of the 6 million people who have fled Ukraine, more than half have crossed into Poland.
Warsaw has consistently argued for tougher Western sanctions on Moscow and has expelled 45 Russian diplomats, prompting a tit-for-tat response from Moscow.
The Russian ambassador was doused with red paint by protesters on Monday as he laid a wreath at the Soviet Military Cemetery in Warsaw.
Russia has demanded an official apology and warned of "further steps" if it is not satisfied with Poland's response.
(Reporting by Reuters; Editing by Kevin Liffey)
