Israel’s foreign ministry says it has banned Green Party leader Zack Polanski from entering the country, after party members adopted a motion declaring Zionism a form of racism.

Israel’s foreign ministry described the motion as a “clear antisemitic text” and beyond “the boundaries of legitimate political debate”.

Polanski did not take part in the vote on Sunday. The motion, which has divided senior party figures, defines Zionism as an ideology supporting “an ethnonationalist Jewish state” and backs a “single democratic Palestinian state in all of historic Palestine”.

It has been criticised by some Jewish groups, who called the motion an “attack on the Jewish community”.

“Zionism is anti-racism, creating a refuge for Jews in their ancient homeland after millennia of persecution outside it,” the Board of Deputies of British Jews and the Jewish Leadership Council said in a statement.

“Branding most British Jews and Jewish institutions ‘racist’ stokes anti-Jewish hatred after a year in which British Jews have been murdered attending their synagogue, stabbed in the streets, and seen their community buildings firebombed.”

Israel’s foreign ministry said the motion was “a stain on the history of the United Kingdom”.

The party’s joint deputy leaders have been at odds over the subject, with Mothin Ali backing the move, and Rachel Millward describing the wording as “problematic”.

But members endorsed the policy motion, which was put forward by a group of activists at the party’s conference in Brighton, by 1,022 votes to 813.

“The real, material, manifestation of Zionism has been the historic and ongoing dehumanisation, displacement, dispossession, disenfranchisement and destruction of Palestinians,” it says.

Discussion about the vote has dominated the conference, and exposed divisions between the party’s newly enlarged membership base under Polanski and its MPs elected at the last general election.

Speaking after the vote, Lubna Speitan, the Green member behind the motion, argued its backers wanted to voice opposition to “racist systems of oppression”.

“We stand united against all forms of racism and discrimination – no exemptions,” she added.

Polanski did not vote in the debate, having left the conference early to campaign in Holborn and St Pancras, where he is standing in a by-election to be the MP. A full list of candidates in the contest can be found here.