The Greens in England and Wales have formally adopted a policy that equates Zionism with racism and calls for Israel to be replaced by a single Palestinian state. This was reported by Qazaqyia.kz citing The Guardian.

The move is expected to be challenged by some party members under equality laws, with one leading KC saying such a case would have a good chance of succeeding.

Members voted at the party's annual conference in Brighton to back a motion that calls for Zionism, the movement for a Jewish state, to be "treated as any other form of racism". It passed by 1,022 votes to 813.

It has been publicly opposed by four of the party's five MPs, although Zack Polanski, the leader of the Greens in England and Wales, has said he does believe Zionism is a racist idea.

The motion, which is now formal policy, calls for a single Palestinian state in place of Israel, "with equal rights for all".

Adrian Ramsay, one of the MPs and a former party co-leader, said after the vote that he was "deeply saddened" by the decision, and that the idea of endorsing a single Palestinian state did not match Green commitments to self-determination.

In earlier voting, an amendment ensuring other parts of Green policy were updated to take account of the motion was backed. Three other amendments, including one that said the motion should not be used to "pressure, proscribe or discipline members based on affiliation with Jewish community institutions", were voted down.

The motion argues that Zionism is necessarily racist as it "privileges one ethnic group on the basis of the subjugation of others". It adds: "This motion is aimed at the political ideology and practice of Zionism, as defined, and not at the religious or ethnic background of those who may identify as Zionists. Not all Jews are Zionists and not all Zionists are Jews ...

"Zionism, as defined above, will be treated as any other form of racism, and this motion will be implemented by the anti-racism policy working group as appropriate and in accordance with its ordinary practice."

According to the Institute for Jewish Policy Research, around two-thirds of British Jews consider themselves Zionists.

While the proposers of the motion argue it will not be used to discipline Jewish members who support Zionism, it is understood that some members are consulting lawyers over whether the policy could be challenged.

Adam Wagner KC, the barrister who led a case that concluded Jeremy Corbyn's Labour broke equalities laws over antisemitism, said that such a case would have a good chance of success.

"I think there is a strong risk that the motion as passed contravenes the Equality Act 2010, which applies to political parties, as it will discriminate against and harass people who hold Zionist beliefs and Jewish people more generally," he said.

"Zionism, defined in the broad sense of supporting the establishment, development and protection of a Jewish nation state in its ancestral homeland, the land of Israel, is likely to be a protected belief under the Equality Act 2010."

He said there was a strong risk that the policy, especially if it resulted in disciplinary action, "will create an intimidating, hostile, degrading, humiliating, or offensive environment for both Zionists and Jewish people, therefore harassing them".

During the lengthy debate, which was for members only, Carla Denyer, the Bristol Central MP who was co-leader with Ramsay, and Caroline Lucas, the former leader who was the Greens' first MP, argued against the plan.

The primary motion, titled "Zionism is racism", had been pushed by a group called Greens for Palestine, which encouraged non-party members to sign up to the party to make sure the policy was debated and adopted. After it was passed, supporters of the idea came to the front of the hall to hug and cheer.

One member who was in the hall and opposed the motion said: "There are now two Green parties – the everyday members, and those who have joined for just one reason, Palestine, and who have no interest in anything else."

A poll by the group Jewish Greens found its membership was split over whether to oppose the motion, while 81% said they did not identify as Zionist. The group is expected to comment publicly on the vote only after consulting members.

There is considerable disquiet among some senior Greens who feel that Polanski, who is Jewish, could have taken a stronger stance on the issue. The party leader, who missed the vote to campaign in Holborn and St Pancras, where he is standing in a parliamentary byelection next week, has justified the motion's argument by pointing to the death toll in Gaza during Israel's assault on the territory.

Asked on Saturday if he believed Zionism was racist, Polanski told the BBC: "Well, in the motion, it is defined as the displacement and genocide of the Palestinian people. I think that is clearly racism."

In a statement after the vote, the Green party said it had been "a serious and deeply felt debate" among members.

It went on: "The Green party is an anti-racist party and has consistently opposed the illegal occupation of both Palestinian and Syrian land, called for an end to arms sales to the Israeli government and spoken out fearlessly about the devastating situation in Gaza and the West Bank.

"Those positions rem"