Jewish organizations around the world are furious with the Ukrainian government ... after a Ukrainian politician used an Anti-Semitic slur in a Facebook rant about Mila Kunis.

The man who set off the controversy is lawmaker Igor Miroshnichenko -- who had written that Mila (a Jew who was born in the Ukraine) is not a true Ukrainian because she's a "zhydovka" ... a word that has been used as a slur against Jewish people since the Holocaust.

After protests by Ukrainian Jews, the Ukrainian government announced the word was OK to use because it appears in the Ukrainian dictionary as a term for a Jew that isn't necessarily a slur.

Now, the famous Simon Wiesenthal Center in L.A. is getting involved -- firing off a letter to the Prime Minister of the Ukraine to "express our outrage and indignation against the slanders of the Svoboda Party directed against the Jewish community in the Ukraine."

In the letter, Rabbi Marvin Hier explains ... the term "zhydovka" translates to "dirty Jewess" ... and was used as an "insidious slur invoked by the Nazis and their collaborators as they rounded up the Jews to murder them at Babi Yar and in the death camps."

The org. has called on the Prime Minister to "publically condemn this attack and to take measures to defeat the xenophobic forces that threaten your democracy."