Earlier Saturday, Abbas had asked Hamas to form the next government, after the new Hamas-dominated parliament was sworn in. In his speech, Abbas said the next government must recognize existing peace agreements and commit to peace negotiations as the ``sole ... strategic choice'' of the Palestinians.
"Hamas reasserts that when it comes to the political program, it rejects negotiations with the occupation (Israel), especially since it (Israel) still practices collective punishment against our people," Hamas spokesman Sami Abu Zuhri told The Associated Press in Gaza City.
Hamas controls 74 of the 132 seats in parliament and Hamas officials have said their top choice for prime minister is the group's Gaza leader, Ismail Haniyeh.
Israel and the international community have said they will not recognize a Hamas government if the group, officially sworn to Israel's destruction, does not renounce violence, recognize Israel and honor all past Israeli-Palestinian agreements.
Hamas' surprise victory in the Jan. 25 parliamentary election ousted Abbas' Fatah Party.
The Islamic militant group has staunchly opposed the interim autonomy agreements, known as the Oslo Accords, which were signed in the 1990s. However, Abbas offered Hamas a sharp warning about breaking the agreements.
"We have not and will not accept any questioning of the accords' legitimacy," Abbas told parliament. "Indeed, from the hour they were endorsed, they became a political reality to which we remain committed."
Mahmoud Zahar, a fiery Hamas leader newly elected to serve in parliament, called Saturday a "historic day," and pledged that Hamas would serve the Palestinian people.
"We have to be the new servants for the Palestinian issue, the Palestinian detainees, the Palestinian land, the Holy Land and also for the people," Zahar told reporters when he arrived at the Gaza government building where the parliament session was to be held via videoconference.
U.S. Secretary of State Condoleezza Rice cautioned Iran and other Middle East powers on Friday of the consequences for the region of giving money to a Palestinian government led by Hamas.
She also expressed doubt that the militant Islamic group could raise badly needed international financing unless it changes its policies.
"I would hope that any state that is considering funding Hamas, a Hamas-led government, would think about the implications of that for the Middle East" and for the goal of peace between Israel and the Palestinians, Rice said.
In an interview with a panel of Arab journalists, Rice delivered a new and blunt warning to Iran.
"Iran has its own troubles with the international community, and it might want to think twice about enhancing those troubles" by bankrolling Hamas, Rice said.
The United States considers Hamas a terrorist group and Iran a patron of terrorism. It has no official dealings with either.
Rice's trip to Egypt, Saudi Arabia and the United Arab Emirates next week is expected to be dominated by discussion of Hamas' surprise election victory and the separate issue of Iran's disputed nuclear program.
Israel, the United States and the European Union, which provide funding for a majority of the Palestinian Authority's budget, have threatened to sever financial ties with the government if Hamas does not meet their demands. Hamas is branded a terrorist group by Europe as well.
Israel was also considering a basket of sanctions against the Palestinian Authority, and its Cabinet will vote Sunday on measures meant to put a stranglehold on the Hamas parliament.
Israeli officials said they were considering sealing the border with Gaza, preventing cargo from going in or out, and barring the 5,000 Gazan workers and 4,000 Gazan merchants from entering Israel for work. The moves would devastate the already impoverished Gaza economy, though Israel would continue to allow humanitarian shipments to cross into the coastal area.
Israel was also likely to freeze the transfer of roughly $55 million in taxes it collects on behalf of the Palestinian Authority each month. The Palestinian government relies on that money to provide a significant portion of the funds needed to pay its 140,000 workers.
"The message that we're trying to get across is that if the Palestinian Authority wants to take care of its people, the first thing it must do is free them from the shackles of terrorism," Israeli government spokesman Raanan Gissin said.
Even before Sunday's Cabinet meeting, Israel prevented lawmakers in Gaza from traveling to the West Bank city of Ramallah to attend the parliament session. Those lawmakers were to participate by videoconference. Another 14 lawmakers serving prison sentences in Israeli jails and two fugitives would also be absent.
Early Saturday, the army set up additional checkpoints on the way to Ramallah, preventing dozens of people from making their way to the city.
Hamas' landslide victory in last month's parliamentary elections were mostly the result of Palestinian anger and frustration with the corruption-riddled Fatah Party, which had dominated Palestinian life for more than four decades.
The 132-member legislature comprises 74 Hamas lawmakers and 45 from Fatah. The rest of the parliament is made up of independents and representatives of smaller parties.
After Abbas officially taps Hamas, the militant group will have five weeks to form the next Cabinet. Hamas officials have said they would nominate Ismail Haniyeh, a relative moderate by Hamas standards, to be next prime minister. But the 46-year-old Haniyeh insisted Friday that a final decision on the new premier had not been made.
Earlier in the week, Hamas chose Abdel Aziz Duaik, a geography professor from the West Bank, as parliament speaker and Zahar as parliamentary faction leader.
In Gaza, about 200 armed Palestinian policemen, some firing in the air, marched toward Gaza's government complex, demanding their overdue salaries just hours before the new parliament was to be sworn in.
The policemen, who were hired just two months ago, said they have yet to be paid for their services. They marched to the building where Gaza's parliament session was to be held.
Some 800 other policemen secured the area around the building, keeping the protesters about 300 yards away. The policemen checked everyone entering the government building where the parliament session was to be held.