The Green Party leader has been reported to the police by Reform UK
Zack Polanski has been scolded by Kieran Mullan after sharing an "appalling" post about Nigel Farage, calling for his beheading.
Speaking to GB News, the Shadow Justice Minister declared the Green leader has a "track record" of sharing controversial social media posts.
In the post, shared via a collaboration on Instagram, a man is depicted wearing a T-shirt which read "We're only making plans for Nigel", alongside a guillotine.
The post was shared with Mr Polanski's 713,000 followers before being deleted.
Reacting to the post on GB News, Mr Mullan argued such posts on social media are "not the sort of thing we should be trivialising".
He said: "It's terrible that that image has been shared and the leader of the Green Party Zack Polanski will have to account for why he did that.
"That's not the sort of thing that we should be trivialising, even a suggestion of violence towards politicians."
The Tory MP stressed following the recent murder of Ann Widdecombe, such a post shared is "appalling".
He told GB News: "This comes on the back of the absolute brutal, horrific murder of Ann Widdecombe that I think shocked the whole whole nation.
"The idea that you might even inadvertently, by not taking necessary care, sharing images like that is appalling."
Mr Mullan accused the Green leader of having a "track record" of sharing controversial social media posts.
He explained: "I'm afraid he has a track record for this, Zack Polanski. I spent some time volunteering as a police officer, and I was appalled to see when he shared criticisms of the two police officers who tackled the knifeman that was attacking the Jewish community in north London, and he was shared a post that was criticising the fact that they had used force.
"These two brave police officers tackling a knifeman who literally just stabbed people and he actually, even after making the social media post, didn't back down, said that the perpetrator was handcuffed at the time, which wasn't true. So he has a track record."
Mr Mullan continued: "And it's not just him, we have all sorts of awful things that Green Party councillors have shared across social media, offensive material in relation to, for example, black politicians in my party, in the Labour Party, referring to them as as coconuts.
"There's just this horrible mess of stuff that's coming out of the Green Party, and Polanski is just adding to that."
Members of Reform UK have also criticised Mr Polanski's decision to share the post, including Treasury Spokesman Robert Jenrick, who declared the move "completely unacceptable".
Mr Jenrick told GB News: "Zach Polanski is the leader of a national political party, and he has collaborated with a post on social media with a guillotine with blood on it, saying this is being prepared for Nigel Farage.
"Zack Polanski knew exactly what he was doing, and he does need to face the consequences."
In a statement, a Green spokesman told GB News: "After attending a public event, Zack accepted a request to collaborate on a post with several images.
"Once this image was brought to his attention he immediately unshared the post. He unequivocally does not support this type of dangerous message."
