UK Prime Minister Andy Burnham has said he will not support his party forming a partnership with the Green Party as long as it maintains a policy of defining Zionism as a form of racism, branding the party "antisemitic".
Speaking in the House of Commons, the prime minister said the motion, backed by Green members at its party conference earlier this month, was "wrong" and "antisemitic" and Labour would have "nothing to do with it".
Green Party members voted earlier this month at the party's annual conference to approve a motion declaring that "Zionism is racism" as party policy.
The party conference vote made the Greens the first major party in the UK to recognise Zionism as a form of racism - and to back a single democratic Palestinian state with equal rights for all ethnic and religious groups, rather than a two-state solution.
The Israeli government responded immediately by banning Green Party leader Zack Polanski (who is himself Jewish), from entering Israel, accusing the Greens of antisemitism.
The United States said it would make "representations" to the British government over the issue, suggesting it could amount to antisemitism.
Polanski said last month, before it was passed, that the motion needed to be amended to say "very clearly and explicitly that this motion safeguards Jewish people."
However, he has defended the substantial part of the motion saying that "the displacement and genocide of the Palestinian people is clearly underpinned by racist ideology" was "obvious".
The motion, having been backed by members, has become party policy but will not necessarily be included in the party's manifesto at the next general election.
The subject was raised during Prime Minister's Questions on Wednesday, when Conservative MP Dame Harriett Baldwin urged Burnham to "rule out co-operating" with the Green Party.
Burnham replied: "Can I condemn the motion that was passed unequivocally."
"It is wrong, it is antisemitic, and this side of the House will have nothing to do with it. We will always take the right response when it comes to any partnerships we have with other parties."
"We cannot support a partnership with a party that holds the position that has recently been adopted."
In response to Burnham's comments, Polanski said: "I'm the only Jewish leader of a political party. I'm a victim of antisemitism every day and I've made it clear Jewish people are welcome in my party."
"You're a prime minister who arms a genocide and locks pensioners up for opposing it." He added that the "blurring of challenging Israel and antisemitism" was "dangerous and irresponsible".
Labour is currently in coalition with the Green Party on local councils in Sheffield, Lewes and Warwick. In more than 10 other areas, Labour run the council with the Greens as part of a broader coalition.
A Downing Street spokesman would not confirm if the prime minister's position extended to local areas or just applied to national government level.
Key backer of the motion Lubna Speitan has defended the motion arguing that it aimed to oppose "racist systems of oppression" adding: "We stand united against all forms of racism and discrimination - no exemptions."
It was also endorsed by prominent Holocaust survivor and activist Stephen Kapos, who said he believed that "Zionism both as an ideology and practice is harmful and has no legitimacy and must be rejected".
