Zack Polanski has been mocked after saying he would try to convince Vladimir Putin to give up his nuclear weapons. The Green Party leader said he wants the whole world to “denuclearise”.

He insisted that he would hold talks with the Russian president if he were to become prime minister. Mr Polanski told Sky News: “I think it’s always impossible until it’s done. I don’t think it’s likely, that’s a different question, but I think the first question has to be, do you believe that we can work for peace and diplomacy in the world?

“Do we believe that we can work with people that we have mass disagreement with that have obviously created an illegal invasion of Ukraine? These are really serious issues.

“And at the same time, I believe we should never leave the negotiating table. Part of that is showing both the moral and courageous leadership to come on TV and say to you, even though this might be a position that’s ridiculed, I don’t think we should find peace and diplomacy ridiculous.

“I think actually the most brave and courageous and authentic thing to do is say, ‘I believe we can have a world without war’.”

Asked if he would negotiate with Putin, Mr Polanski added: “Undoubtedly. I think it would be sociopathic behaviour to say you wouldn’t negotiate with the president or a prime minister of any country.”

But Reform UK’s head of policy, Zia Yusuf, mocked Mr Polanski as he referred to a 2013 interview when the Green leader claimed he was able to help women increase the size of their breasts using his mind when working as a hypnotherapist.

Mr Yusuf said: “Zack, there’s as much chance of you persuading Putin to give up his nukes by asking nicely as there is of … oh I don’t know … growing the size of a woman’s breasts by hypnotising them.”

The Green leader hit back: “Your daily reminder that the Welsh leader of Reform took bribes from Putin’s Russia.”