The Tories have called on John Swinney to block a Scottish Green Party leader from appearing at the SNP conference this weekend.
Russell Findlay, the Conservative leader, accused the Greens of “ugly antisemitism”.
It comes after co-leader Ross Greer largely backed an English Green motion describing Zionism as a form of racism.
The motion also effectively called for the end of Israel by backing Palestine as the one state in the region.
Mr Findlay also attacked Green MSP Ariane Burgess for reportedly liking a social media post by an ex-Green MSP which featured an Israeli flag with a blood-covered swastika in it, although she later said it was an “error”.
Gillian Mackay, the party’s co-leader, is set to speak at a panel on independence at the SNP conference in Aberdeen on Saturday.
Some members have reportedly expressed frustration at her planned appearance due to her stance on oil and gas.
“John Swinney has a simple choice,” Mr Findlay said, “either legitimise the Scottish Greens’ antisemitism by welcoming them to SNP conference or ditch them.
“Swinney says he respects Scotland’s Jewish community. If so, then he won’t give his Green friends a platform.”
The Scottish Tory leader accused the First Minister of “indulging in pro-Palestine posturing to the detriment of Scotland’s valued Jewish community”.
He said Mr Swinney “can no longer ignore” the Greens’ “ugly antisemitism”.
He added: “Scotland is suffering from the disturbing phenomenon of hard-left politicians joining forces with Neo-Nazis and Islamo fascists in their shared hostility towards Jews, which they disguise as being anti-Israel or anti-Zionist.
“I’ve spoken with SNP members who say they’re sickened by the Greens presence, due to their antisemitism but also their anti-oil and gas policies.”
An SNP spokesperson said: “The First Minister has been clear he does not agree with the Green conference motion.”
The Greens have been approached for comment.