JERUSALEM — Hamas, a fundamentalist terrorist group committed to Israel’s destruction, appears poised to form the next Palestinian government.

In a stunning development, unofficial returns indicated that Hamas, in its first-ever run for Parliament on Jan. 25, had taken a majority of the 132 seats in the Palestinian Legislative Council.

The Cabinet led by Palestinian Authority Prime Minister Ahmed Qurei — a member of the Fatah movement, which has dominated Palestinian politics for decades — resigned Thursday after Hamas’ victory became apparent.

P.A. President Mahmoud Abbas is elected separately, and his position was not affected by the vote, but it wasn’t clear Thursday if he would remain in office if Parliament is dominated by radicals whose platform he rejects.

Hours after the unofficial results showed Hamas’ victory, supporters of the terrorist group poured into Parliament and clashed with Fatah men, raising the Hamas flag over the building. The two camps threw stones at each other, breaking windows in the building, The Associated Press reported.

Hamas’ victory came as a shock to Israel and the international community, which had been grappling with the question of how to deal with a Fatah-led P.A. government that included a few Hamas members, or with Hamas as a strident parliamentary opposition.

Instead, they will have to contend with a Palestinian legislature dominated by a terrorist group that utterly rejects the Jewish state and has refused to disarm its militia or disavow terrorism, as required by the internationally backed “road map” peace plan.

President Bush said the United States would not deal with Palestinian leaders who call for Israel’s destruction.

“I don’t see how you can be a partner in peace if you advocate the destruction of a country,” he said in a news conference Thursday.

Bush also said that he and U.S. Secretary of State Condoleezza Rice were urging Abbas, commonly known by the nom de guerre Abu Mazen, not to resign. He said Rice will speak with leaders of the diplomatic “Quartet” — the United States, United Nations, Russia and the European Union — that has been guiding Mideast peace efforts.

Israeli officials were noticeably silent in reaction to the results; they said there would be no official reaction until the Palestinians announced final results from the elections.

But on Jan. 25, Acting Israeli Prime Minister Ehud Olmert said that Israel could not accept Hamas as part of the Palestinian Authority if the group kept its arms and its goal of destroying Israel.

“I will not negotiate with a government that does not meet its most basic obligations to fight terrorism,” Olmert said in a meeting with visiting U.S. Sen. Joseph Biden (D-Del.). “We are prepared to assist the Palestinians and Abu Mazen very much, but they must meet their commitments.”

Hamas leaders said Thursday that they would hold talks on forming a coalition government.

“We are convinced we will be partners with the other factions,” a Hamas official said.

However, Fatah official Saeb Erekat said after a meeting with Abbas that Fatah would stay on the sidelines.

“We in Fatah will not join them. We will be a loyal opposition and rebuild the party,” he said.

Hamas has carried out scores of suicide bombings against Israelis over the past decade, but largely has kept to a truce that most terrorist groups declared in early 2005. Senior Hamas official Mahmoud al-Zahar said Thursday that the group would maintain the cease-fire if Israel does likewise.”

“If they are going to continue commitment to what is called quietness, then we will continue, ” he said in an interview with A.P. Television News. “But if not, then I think we will have no option but to protect our people and our land.”

European leaders said they would not deal with a Palestinian government that advocated violence.

“What is important is that we state we are happy to work with any government if that government is prepared to work by peaceful means,” European External Relations Commissioner Benita Ferrero-Waldner told a European Parliament committee, according to Ha’aretz.