– An Israeli official said Wednesday that Israel was willing to extend a three-day cease-fire in the Gaza Strip but the offer was not immediately accepted by Hamas, as Egyptian officials mediating indirect talks struggled to overcome sharply conflicting demands in hopes of fashioning a long-term truce.

Egypt's intelligence chief, Mohammad Farid al-Tohamy, held separate meetings in Cairo with Palestinian and Israeli delegations. Egyptian Foreign Minister Sameh Shukri said he hoped a 72-hour cease-fire, which is set to expire early Friday, would be extended to allow further negotiations.

The United States sent Frank Lowenstein, the acting special envoy for Israeli-Palestinian negotiations, to Cairo to assist.

The United Nations' special envoy to the Middle East, Robert Serry, also was on hand, as was Tony Blair, representative of the so-called Quartet of Middle East mediators, which includes the United States, the United Nations, the European Union and Russia.

But even as Israel said it was willing to extend the temporary cease-fire, Hamas denied Arab media reports that agreement had been reached to prolong the lull until Monday.

"Israel agreed to an unconditional cease-fire and is willing to continually extend it," a senior Israeli official said.

However, Mousa Abu Marzouk, the second-ranking political leader in Hamas, denied that any deal had been reached on an extension.

The armed wing of Hamas said it remained on standby for further orders, and Israeli Prime Minister Benjamin Netanyahu said, "We are prepared for any case in which this cease-fire is violated."

Al-Tohamy met Wednesday with the Palestinian team, composed of Hamas, Islamic Jihad and other Palestinian factions and headed by a representative of the Fatah Party of Palestinian Authority President Mahmoud Abbas. A three-member Israeli team arrived later in Cairo for further talks.

A significant roadblock

A major sticking point appeared to be Israel's demand to prevent the rearming of Hamas as a step toward demilitarizing the Gaza Strip by ridding it of rockets and weapons stocked by militants.

Hamas has called any move against the group's weapons a "red line" that is not up for debate.

Egyptian Foreign Minister Shukri told a news conference that the issues at stake were "complicated and not easy," and that talks were focusing on easing Israeli-imposed closures of Gaza's ­borders to "meet the demands of the Palestinian people."

The Palestinian delegation is demanding the removal of border closures imposed by Israel and Egypt after Hamas seized control of Gaza in a brief civil war in 2007.

Hamas has called for the opening of a border crossing with Egypt for movement of people and goods, but the Egyptian government, which is hostile to the Islamist group, has severely limited passage of Palestinians from Gaza.

At a news conference in Washington, President Obama expressed sympathy for granting residents of Gaza freedom of movement. "Long term it has to be recognized that Gaza cannot sustain itself closed off from the world," he said, adding, "I have no sympathy for Hamas, but I have great sympathy for ordinary people who are struggling."

An improbable first step

Still, easing Gaza's isolation seemed an unlikely quick step.

One proposal for reopening the crossing would provide for the stationing of Palestinian Authority forces there. Netanyahu said Wednesday that Israel was "prepared to see a role for them" in future arrangements in Gaza.

But a statement from Egyptian intelligence suggested that Egypt was not prepared to be the only means for Gazans to trade.

Netanyahu on Wednesday said he disagreed with assertions that Israel's campaign, which has killed more than 1,800 Palestinians, had been a disproportionate response to Hamas' rocket attacks, which killed three civilians inside Israel. Sixty-four Israeli soldiers died.

United Nations Secretary-General Ban Ki-moon raised the issue Wednesday before the U.N. General Assembly. He said that the U.N. recognized Israel's right to defend itself, but "the horror that was unleashed on the people of Gaza" during the conflict raised serious questions about respect for international law and proportionality.