RAMALLAH, West Bank -- With solemn speeches and an incantation of Quranic verses, a new Palestinian legislature dominated by the Islamist group Hamas was sworn in yesterday, setting the scene for a tense confrontation with Israel.

Palestinian Authority President Mahmoud Abbas called upon the incoming government, which Hamas will form in the coming weeks, to honor past accords with Israel and continue to seek a negotiated peace that would lead to side-by-side states.

"We ... will continue our commitment to the negotiation process as the sole political, pragmatic and strategic choice," Mr. Abbas told lawmakers, diplomats and dignitaries who assembled in Ramallah for the swearing-in ceremony, together with a parallel gathering in the Gaza Strip.

Hamas leaders pledged to try to resolve political differences with moderates such as Mr. Abbas through dialogue, but several of its leading lawmakers said negotiations with Israel did not figure in the group's plans.

Mr. Abbas "was elected according to one platform, and we were elected according to another," said Ismail Haniyeh, who is considered the likely Hamas candidate for prime minister. He led the militant group's slate of candidates to a decisive victory in Jan. 25 parliamentary elections, the Palestinians' first in a decade and the first in which Hamas participated.

Israel, which has threatened to impose sweeping sanctions against the Hamas-led government, has said it will have no dealings with the government unless it renounces its call for Israel's destruction, recognizes the Jewish state's right to exist and disarms its military wing.

"As of today, the rules of the game have changed," said a senior Israeli official, speaking on condition of anonymity because the government's position would be ratified formally at a meeting of the Cabinet today. "The Palestinian Authority ... has become a hostile entity vis-a-vis Israel. That has far-reaching implications."

Steps being weighed by Israel include an immediate freeze on the transfer of tax revenues to the Palestinian Authority, the closing of border crossings with the Gaza Strip and a freeze on construction of Gaza's airport and seaport.

It is by no means clear that Mr. Abbas has the authority to set any preconditions for Hamas' participation in the Palestinian government, as Israel has demanded. The group won 74 of the 132 seats in the legislature, and by law the largest party in Parliament is asked to put forth candidates for prime minister and the Cabinet, a process that could take up to five weeks.

Mr. Haniyeh, who is considered a pragmatist, has hinted that the group will present a government made up of the group's less radical elements, and some non-Hamas members.

"We are eager ... to open the door wide for Palestinian technocrats and professionals, in order to offer a government that wins the confidence of the Parliament, and is respected by the Palestinian people and concerned parties," he told reporters after the swearing-in ceremony.

Israel and Hamas appeared to be trying to position themselves for their looming confrontation by not yielding too much ground early on.

If the Israeli government, led by acting Prime Minister Ehud Olmert, puts harsh sanctions in place now, it could portray rescinding them later as a gesture of statesmanship. Such a step could wait until after Israel's own parliamentary elections, fewer than six weeks from now, in which Hamas has become a major campaign issue.

Hamas, while balking at formally renouncing its call for Israel's destruction, has signaled readiness to call for a long-term "hudna," or truce. It also has moderated its position somewhat by indicating it will seek the creation of a Palestinian state only in the West Bank and Gaza, rather than in all of historic Palestine -- which encompasses Israel.

And while refusing to disarm, Hamas started to turn away from its armed campaign when it began running in Palestinian local elections in 2005. The group, which was responsible for dozens of suicide bombings over the course of the Palestinian uprising, or intifada, has not carried out such a suicide attack inside Israel for more than a year.

As the militant group moves to assert some degree of control, delicate internal negotiations lie ahead. Under Palestinian law, government powers are divided between the executive branch and the Parliament. Mr. Abbas wields control over diplomacy, peace talks and most elements of the security forces, while Cabinet ministers oversee day-to-day affairs.

The swearing-in ceremony was replete with symbolic overtones not only of the Palestinians' conflict with Israel, but the divide between the triumphant Hamas and Fatah, the long-ruling party it soundly defeated. Fatah lawmakers interrupted Mr. Abbas' speech at several points with applause; Hamas lawmakers remained silent as the Fatah standard-bearer spoke.

More than a dozen lawmakers who were either in jail or fugitives were counted as "present" during the roll call.

Israel had forbidden most of the new lawmakers from Gaza, including senior Hamas figures such as Mr. Haniyeh and Mahmoud Zahar, from traveling to the West Bank. So they took part via a sometimes-balky video teleconferencing link from the legislative building in Gaza City.

In Ramallah, Mr. Abbas chose to convene the gathering at his own headquarters rather than the Parliament building, possibly as a means of underscoring his personal authority.