Palestinian Prime Minister Ismail Haniyeh said Friday that Israel's offensive in Gaza was aimed at toppling the Hamas-led government, but assured his people he is working with international mediators to try to resolve the stand-off over a kidnapped Israeli soldier.

Israel kept up the pressure in Gaza, destroying the interior minister's office and targeting a car carrying Islamic Jihad militants in an air strike.

With the crisis threatening to boil over into major fighting, the U.N. Security Council held an emergency debate on the situation, with the Palestinians pressing for a resolution condemning Israel's actions and demanding a halt to all military operations. But no resolution was circulated to council members, apparently because of opposition by the U.S., Israel's closest ally.

Early Saturday, the militants holding the soldier issued a new set of demands, calling on Israel to halt its offensive in Gaza and ordering the release of 1,000 prisoners.

The demands were laid out in a joint statement by the militant wing of the ruling Hamas party, and two smaller militant groups with close ties to Hamas — the Popular Resistance Committees and the Army of Islam. The three groups have claimed responsibility for Sunday's abduction of Cpl. Gilad Shalit in a cross-border raid.

Earlier this week, the same groups called for the release of all Palestinian women and minors held by Israel in exchange for information about Shalit. Saturday's statement, like the earlier one, did not promise to release Shalit or give any information about his condition.

Israeli defense officials believe he suffered slight wounds, but is still alive. Israel has ruled out a prisoner swap.

In Gaza City, Haniyeh urged his people to remain steadfast in the face of the Israeli offensive. Though he did not directly address Israel's demand that Palestinian militants hand over the abducted soldier, he implied the government would not trade him for eight Palestinian Cabinet ministers arrested Thursday.

He also accused Israel of using the kidnapping as a pretext for launching a major offensive with the real aim of bringing down his government.

"This total war is proof of a premeditated plan," he said.

Haniyeh spoke in a sermon at a Gaza mosque on Friday, the Muslim day of worship, as Hamas gunmen stood guard outside. It was his first public appearance since Israeli Cpl. Gilad Shalit, 19, was kidnapped Sunday in a militant raid on an army post that sparked the crisis and sent Hamas' top leaders into hiding.

Israel sent troops into southern Gaza on Wednesday — the first major raid into the territory since Israeli soldiers pulled out last year after a 38-year occupation — and began a wave of airstrikes across the territory.

The United Nations said a strike that destroyed Gaza's only power plant had pushed Gaza to the edge of a humanitarian crisis, and the International Committee of the Red Cross said it was working to get the military blockade of Gaza lifted for aid shipments.

With troops massed on the border, Israeli officials on Thursday postponed a planned invasion of northern Gaza as international mediators worked to find a way out of the stand off.

Haniyeh said Friday that he was in contact with Arab, Muslim and European leaders to try to resolve the crisis, "but this Israeli military escalation complicates matters and makes it more difficult."

The Bush administration called Friday on the Palestinians to free Shalit and on Israel to practice restraint.

"We are encouraged by the fact that the Israelis are standing down in Gaza and that Hamas is talking openly about repatriating the soldier, and we continue to watch the developments," White House spokesman Tony Snow told reporters aboard Air Force One.

Egyptian President Hosni Mubarak said in an interview published in Egypt's Al-Ahram newspaper Friday that his government had been holding talks with Hamas leaders, who agreed to conditionally release Shalit, but Israel had not yet accepted the agreement.

He added that Israeli Prime Minister Ehud Olmert had promised him not to rush into a military offensive, but to "give additional time to find a peaceful solution to the problem of the kidnapped soldier."

Israeli officials said they did not know of such an agreement, and denied cooperating in any talks.

"There are no negotiations," government spokesman Asaf Shariv said.

Palestinian President Mahmoud Abbas met in Gaza on Friday with European Union Mideast envoy Marc Otte to discuss the situation.

"We hope that today or tomorrow the Egyptian brothers, especially now that Mubarak is involved, will reach an acceptable solution, a solution that will avoid suffering for the Palestinian people," Palestinian legislator Mohammed Dahlan said after the meeting.

Mohammed Nazal, a Damascus-based Hamas leader, said he believed Israel was stalling.

"They're buying time until they can locate the soldier through intelligence and then try to free him," he said.

With negotiations appearing to bear no fruit, Israel continued its air assault in Gaza on Friday.

In a pre-dawn attack, Israeli missiles destroyed Interior Minister Said Siyam's fourth floor office and the ground floor office of one of his bodyguards. The floors in between — where passports and ID cards are printed — were left untouched.

The military said it targeted the ministry because it was "a meeting place to plan and direct terror activity."

Late Friday, Israeli airstrikes targeted militant training facilities in northern and southern Gaza, the army said. The airstrikes continued after midnight, targeting access routes in central Gaza, the army said. There were no reports of injuries.

On Friday evening, an Israeli airstrike targeted a car in Gaza City. Witnesses said a missile exploded next to the car, lightly wounding three members of the violent Islamic Jihad group.

Khaled Abu Hilal, an Interior Ministry spokesman whose office also was destroyed in an airstrike Friday, called on Palestinian security forces to mobilize to repel an Israeli attack.

However, the ministry, which is supposed to run the security forces, was stripped of much of its authority by President Abbas in a power struggle following Hamas' victory in January parliamentary elections.

Pushing against Hamas on all fronts, the Israeli Interior Ministry on Friday revoked the Jerusalem residency rights of four senior Hamas officials. The unprecedented measure takes away their right to live in the holy city and travel within Israel freely.

In his speech Friday, Haniyeh said his government is continuing to function despite the arrests of the Cabinet ministers.

On Friday, Israel's army said it also attacked a cell that attempted to fire an anti-tank missile at Israeli forces in southern Gaza. Mohammed Abdel Al, 25, a local leader of the Islamic Jihad militant group, died of wounds he suffered in that airstrike, becoming the first casualty in Israel's offensive.

In the West Bank, Israeli troops exchanged gunfire with militants at a cemetery in Nablus. Palestinian security officials said one militant was killed, but the army said two militants died.