The latest airstrikes came after Palestinian President Mahmoud Abbas indicated the crisis over the soldier was coming to a head.
The attack on the premier's office set the building ablaze, but because of the late hour — 1:45 a.m. it was empty, witnesses said. One bystander was slightly injured, hospital officials said.
In a statement about the attack, the Israeli military said it would "employ all means at its disposal ... to secure the safe return" of the soldier, Cpl. Gilad Shalit, 19.
Inspecting his burning office, Haniyeh called the Israeli attack senseless. "They have targeted a symbol for the Palestinian people," he said.
In other airstrikes after midnight, Israeli aircraft hit a school in Gaza city and Hamas facilities in northern Gaza, where a Hamas militant was killed and another wounded, Palestinian officials said. The military said they were "planning terror attacks against Israel." The 34-year-old Hamas gunman was the second militant killed in the five-day Israeli operation.
With Israeli tanks parked in southern Gaza for the first time since Israeli pulled out of the territory last summer, Abbas said Saturday that the coming hours were "critical, sensitive and serious" to resolving the crisis.
On Saturday, Hamas demanded release of more than 1,000 prisoners held by Israel, but Israel rejected that out of hand, declaring that it will not negotiate with the militants holding the soldier, Cpl. Gilad Shalit, 19, since last Sunday, when militants tunneled under the border and attacked an Israeli post, killing two other soldiers.
Abbas said a solution must be found. "Regarding the soldier, we will surely reach an agreement. It is not a dead end. People want an acceptable solution," he said.
Abbas, a moderate who has been in a power struggle with Hamas, warned that if a solution is not found, Israel might take further military steps.
"I am afraid that what is to come is going to be dangerous because we can't bear another serious aggression and another occupation. What is to come may be more difficult," he said. "What is important is to protect national unity. to protect our people and to avoid bringing danger and disaster to the nation."
Israeli Prime Minister Ehud Olmert has said Israel does not intend to reoccupy Gaza. On Thursday Olmert called off a planned invasion of northern Gaza, leaving Israeli tanks and troops parked in the south, where Israel believes the soldier is being held.
Defense Minister Amir Peretz met with senior security officials Saturday night and then called U.S. Secretary of State Condoleezza Rice to urge the Bush administration to step up pressure on Syria to work for Shalit's release, Israeli officials said. The officials spoke on condition of anonymity since they were unauthorized to make a formal statement. Israel, called U.S. President George W. Bush on Saturday and talked for 30 minutes about the crisis.
"The president said that the initial goal should be freeing the Israeli soldier — that is the key to ending the crisis," said Frederick Jones, spokesman for the National Security Council at the White House.
There has been no direct evidence of the condition of the soldier since he was abducted a week ago during a militant raid on an Israeli army post just outside Gaza that killed two soldiers and two of the attackers.
Ziad Abu Aen, a Palestinian deputy minister and a Hamas official, said Saturday that "mediators" told him Shalit had received medical treatment for the wounds he sustained in the raid and was in stable condition.
"He has three wounds," Abu Aen said at a news conference in the West Bank city of Ramallah. "I guess shrapnel wounds."
Another Hamas official, Osama Muzami, dismissed that. He said only the military wing of the Islamic militant group knows about the condition of the soldier.
The Hamas-affiliated militants holding Shalit initially said they would trade information about him for all Palestinian women and underage prisoners being held in Israeli jails. The militants raised their demands Saturday, calling for an end to the Israeli offensive and the release of 1,000 additional prisoners held by Israel, including non-Palestinian Muslims and Arabs.
The new demand appeared aimed at rallying support in the Arab world.
Israel has ruled out any compromise with the militants, saying it would only encourage more abductions.
Israel has also blamed Syria for the abduction, arguing that it harbors Hamas' top leaders, who are based in Damascus.