JERUSALEM -- Stephen W. Hawking, the University of Cambridge physicist and cosmologist, has pulled out of a high-profile conference to be held here in June in order to support an academic boycott of Israel, conference organizers and the university said on Wednesday.
The academic and cultural boycott, organized by international activists to protest Israel's policies toward the Palestinians, is a heated and contentious issue; having Dr. Hawking join it is likely to help the anti-Israel campaigners significantly.
"Never has a scientist of this stature boycotted Israel," said Yigal Palmor, the spokesman for Israel's Foreign Ministry.
Organizers of the fifth annual Israeli Presidential Conference, held under the auspices of President Shimon Peres, said they had received a letter over the weekend from Dr. Hawking, a longtime Cambridge professor, announcing his decision.
Cambridge issued a statement indicating that Dr. Hawking had told the Israelis that he would not be attending "based on advice from Palestinian academics that he should respect the boycott," according to The Associated Press.
Earlier, the university's director of communications, Tim Holt, said by telephone that Dr. Hawking, 71, had withdrawn from the Israel trip for health reasons. The university later said it had been told otherwise by Dr. Hawking's office.
Israel Maimon, the chairman of the conference, strongly criticized the professor's decision, saying in a statement, "The academic boycott of Israel is in our view outrageous and improper, certainly for someone for whom the spirit of liberty lies at the basis of his human and academic mission."
Mr. Maimon, a lawyer and a former Israeli government cabinet secretary, added: "Israel is a democracy in which all individuals are free to express their opinions, whatever they may be. The imposition of a boycott is incompatible with open, democratic dialogue."
There was no immediate comment from Mr. Peres's office.
The Guardian newspaper first reported Dr. Hawking's change of mind and cited a statement by the British Committee for the Universities of Palestine, which The Guardian said was published with Dr. Hawking's approval. It described the cancellation as "his independent decision to respect the boycott, based upon his knowledge of Palestine, and on the unanimous advice of his own academic contacts there."
Dr. Hawking last visited Israel and the Palestinian territories in 2006 at the invitation of the British Embassy in Tel Aviv.
Matthew Gould, the British ambassador to Israel, spoke out against the academic boycott when he received an honorary doctorate from Ben Gurion University of the Negev in December. "We believe that boycotts divide people and reduce understanding," he was quoted as saying, "when what we need is to bring people together."
The Oxford University Student Union decisively rejected a motion supporting a boycott of Israel in a vote in February.
Under pressure from pro-Palestinian activists, a string of high-profile artists have canceled performances in Israel in recent years, among them the Pixies, the American alternative rock band; the British rocker Elvis Costello; and Gil Scott-Heron, the American rap poet and musician who died in 2011.
Other performing artists, like Rihanna, Elton John, Rod Stewart and Madonna, have given concerts in Israel in the last few years. Barbra Streisand is slated to give two concerts in Tel Aviv in June and to perform at the Israeli Presidential Conference in honor of Mr. Peres's 90th birthday this summer.
The conference, called "Facing Tomorrow 2013," is billed as a meeting place for exploring the developments shaping the future of Israel, the Jewish people and the world. Its program includes former heads of state, academics, artists and business executives. Former President Bill Clinton is to receive an award from Mr. Peres.
Also listed among the speakers is Munib al-Masri, a Palestinian tycoon from the West Bank city of Nablus who has been working to promote internal Palestinian reconciliation.
This article originally appeared in The New York Times.