Zack Polanski has said Zionism in its current form is racist, that no country has a right to exist and that the controversial Green party motion on the issue was not controversial.

The leader of the Green party in England and Wales gave an unapologetic interview to the BBC on Sunday two weeks after his party approved a motion equating Zionism with racism.

Polanski did not attend the vote, prompting accusations of a lack of leadership, but he made clear he agreed with the broad thrust of it even if he felt it was unhelpful to have what he called a “debate about semantics”.

Asked by the BBC’s Laura Kuenssberg whether he thought Zionism was racist, Polanski said: “I don’t think this is actually controversial.

“What’s controversial is that 75,000 Palestinians have been murdered in the last few years, including more child amputees than ever in modern history. So when you take that to account, the fact that they’re being murdered because they’re Palestinian – that’s very obviously a racist ideology.”

He added: “I think Zionism is racism in the practical application of it. Now the conference had a debate about the motion, about the word. I said I think debates about words are unhelpful, and I still think that.”

Asked whether he believed Israel had a right to exist, Polanski, who is Jewish, said: “I don’t think any state has a right to exist under international law,” adding that the idea of a two-state solution was “for the birds” given Israel’s opposition to it.

The Green leader also insisted he had no regrets about the way he had handled the recent controversy, despite criticism from some prominent Jewish Green members, including Vivien Lichtenstein, the head of the Jewish Greens.

“I’m not sorry at all,” he said. “Vivien is someone I’ve had respect for and do have respect for, and partly co-founded the Jewish Greens together … Actually, when the Jewish Greens were surveyed about this motion, a majority supported it.”

Polanski’s defiant interview comes after the most difficult two weeks of his leadership of the party since he took over last September, during which he has endured the fallout from the conference vote and lost the Holborn and St Pancras byelection.

His strategy of shifting his party to the left, focusing on economically populist ideas and leaning into debates on Palestine and Gaza, initially paid dividends, with the party jumping from about 10% in the polls to 18% earlier this year.

In recent months, however, the party has tumbled, beset by questions over his tax affairs, a public spat with the police after the Golders Green attack and the recent row over Zionism.

He said on Sunday that he was confident voters would return to his party once they had seen more of Andy Burnham’s leadership of the country. “People more and more will see from Andy Burnham a change in rhetoric, but not a change in action, and know the Green party have been right all along,” he said.