Britain’s Green Party voted Sunday to classify Zionism as a form of racism, prompting sharp condemnation from British Jewish organizations and Israel, whose government said the decision effectively makes the party “a body that gives legitimacy to terrorism”.

The party, which won about 6% of the national vote in the 2024 election, described Zionism as “an ethnonationalist political project.” Delegates also reaffirmed their demand that Britain’s Labour government halt all arms trade with Israel.

“The motion also restates the Green Party’s backing for the ​right to self-determination and calls for the establishment of a single democratic state throughout historic Palestine,” the party said in a statement.

Zionism remains a deeply disputed political concept. It played a central role in the establishment of modern Israel during the 20th century, while Jewish organizations commonly describe it as supporting the Jewish people’s right to national self-determination.

Green Party members approved the motion by 1,022 votes to 813, despite resistance from a number of senior party figures. Leader Zack Polanski, who is campaigning for a seat in Parliament in Thursday’s election in the London constituency previously represented by former Prime Minister Keir Starmer, did not participate in the vote.

British Jewish organizations strongly criticized the decision.

“The Green Party has made antisemitism party policy and become a racist party,” the Movement for Progressive Judaism said. The organization also cautioned that the participation of some Jews in supporting the motion does not prevent the policy from being used to discriminate against other Jews.

Israel also responded forcefully. Foreign Minister Gideon Sa’ar decided to bar Polanski from entering Israel, according to the Israeli Foreign Ministry, which announced the decision Sunday on X.

The ministry said the Green Party resolution “constitutes a clear antisemitic text according to the IHRA (International Holocaust Remembrance Alliance) definition, as it denies the Jewish people’s right to self-determination,”.

Mothin Ali, the Green Party’s deputy leader and a supporter of the measure, said the extensive Palestinian death toll during Israel’s war against Hamas was central to the debate. The conflict followed Hamas’ deadly 2023 attack at an Israeli music festival.

“The motion defines Zionism quite clearly. It defines it as an ethnonationalist movement. It defines it as ethnic ​cleansing. It defines it as genocide,” Ali said.

The British government has characterized actions by Israeli settlers in Judea and Samaria as amounting to ethnic cleansing, while maintaining that determinations over whether other Israeli conduct constitutes genocide should be made by courts. Israel rejects allegations of both ethnic cleansing and genocide.

Israel called on Britain’s other political parties to denounce the Green Party’s decision.

“The Greens have adopted not only the green of Hamas, but ⁠also its ​ideology: the elimination of the State of Israel through armed struggle,” it said.

Polanski and other senior Green Party officials defended their position, saying they would “continue to call out the heinous crimes of the Netanyahu government,” while maintaining that “there is no conflict between supporting the rights ​of Palestinians and the rights of Jewish people.”

The vote places the Green Party at the center of an increasingly contentious British political debate over Israel, Palestinian rights, antisemitism and the meaning of Zionism.