The UK's left-wing Green Party on Sunday voted to define Zionism as racism at its annual conference.
Members of the Green Party, which has five MPs in Britain's 650-seat parliament and has enjoyed gains in recent local elections and by-elections, backed the motion by 1,022 votes to 813.
Under the motion, Zionism would be "treated as any other form of racism", while the party supports the establishment of a "single democratic Palestinian State in all of historic Palestine".
"This has been a serious and deeply felt debate within our membership," a Green Party spokesperson said.
The Greens have seen a surge in support under Zack Polanski, attracting voters dissatisfied with the centre-left Labour government's stance on Israel's genocidal war on Gaza.
The motion has also exposed divisions within the party. Polanski — who is currently running to become an MP in former prime minister Keir Starmer's London constituency — did not vote on the motion.
At least three of the party's five MPs opposed the motion, although Polanski said earlier this week that the "displacement and genocide of the Palestinian people" was "clearly racism".
Israel's Foreign Ministry condemned the decision, saying the policy went "far beyond the boundaries of legitimate political debate".
"Every political party in Britain, first and foremost the governing Labour Party, must unequivocally reject this twisted resolution," the ministry said.
UN investigators have concluded that Israel has committed genocide against Palestinians in Gaza, citing mass killings, serious bodily and mental harm, starvation and the systematic destruction of healthcare and education systems.
More than 73,500 Palestinians had been reported killed and over 174,000 injured since October 2023, while UN reporting has documented widespread destruction of civilian infrastructure across the besieged enclave.
