Zack Polanski was denied entry to Israel on Sunday. Polanski serves as leader of the Green Party of England and Wales.
Israeli Foreign Minister Gideon Sa'ar made the decision in coordination with the relevant authorities.
Party adopts policy on Palestine at conference
Members of the Green Party approved a motion at a conference in Brighton making opposition to Zionism official party policy.
The motion defined Zionism as a racist ideology. It also expressed support for a single democratic Palestinian state throughout the historic territory of Palestine, in which everyone would have equal rights.
Israeli Foreign Ministry issues accusations
The Israeli Foreign Ministry argued that the Green Party considers armed resistance legitimate and rejects the Jewish people's right to self-determination.
The ministry claimed that the party's policy amounted to antisemitism under the definition of antisemitism used by the International Holocaust Remembrance Alliance.
The Israeli Foreign Ministry had previously accused the Green Party of being a "terror supporter." The ministry called on political parties in the United Kingdom, including the governing Labour Party, to reject the motion.
Green Party rejects accusation
The Green Party rejected equating opposition to Zionism with antisemitism. The party described Zionism as an ethnic-nationalist political project.
The party also reiterated its support for the Palestinians' right to self-determination and right of return, and advocated a comprehensive arms embargo on Israel.
