At least 40 air strikes targeted ministry and security buildings, mostly in Gaza City, sources and witnesses told Agence France-Presse (AFP).
Moawiya Abu Hassanein, the director of Gaza's emergency services, said at least 10 Palestinians were killed and more than 40 wounded in the new raids.
This takes to at least 360 Palestinians killed and 1,690 wounded since Israel unleashed its military juggernaut against the coastal enclave on Saturday.
Among the buildings struck were those housing the offices of the prime minister, the defense, education, foreign, and finance ministries, as well as the Islamic University.
The foreign ministry was completely destroyed as were nearby homes.
The finance ministry was also completely leveled, and fires broke out near the bombed sites.
The municipal council building in the southern town of Bani Suhaila was bombed, as were police posts in Qarara, Beit Hanun and Beit Lahia.
The strikes knocked out the electricity in Gaza City and to the north and flattened dozens of houses.
Israel vowed on Monday to raze every single structure in the Gaza Strip during its ongoing blitz of the Palestinian enclave.
"After this operation there will not be a single Hamas building left standing in Gaza, and we plan to change the rules of the game," said armed forces deputy chief of staff Brigadier General Dan Harel.
"We are hitting not only terrorists and launchers, but also the whole Hamas government and all its wings," he explained.
"We are hitting government buildings, production factories, security wings and more."
Strikes on more than 325 sites since Saturday reduced dozens of buildings to rubble, overwhelmed hospitals with wounded and filled Gaza's deserted streets with smoke and fire.
Harel threatened that was just the beginning.
"The worst is not behind us, it is still ahead of us," he said ominously.
Israel snubbed Tuesday calls for the UN chief and French President Nicolas Sarkozi for a ceasefire.
"There is no room for a ceasefire," Interior Minister Meir Sheetrit told Israel Radio as Israel's aerial offensive on Gaza entered a fourth day.
"The government is determined to remove the threat of (rocket) fire on the south.
"Therefore the Israeli army must not stop the operation before breaking the will of Palestinians, of Hams, to continue to fire at Israel," he said.
"That's the goal and it must be achieved."
But Deputy Prime Minister Haim Ramon said the offensive's goal "is to topple Hamas."
Israeli Deputy Defense Minister Matan Vilnai said the military "has made preparations for some long weeks of action."
Israeli tanks amassed at the borders with the Gaza Strip are standing by to join the "all-out" war Defense Minister Ehud Barak declared.
Karen Abu Zayd, commissioner of the UN Relief and Works Agency which helps Palestinian refugees, said Israel had violated an informal truce.
"What we understood here (was) that there was a 48-hour lull to be called, and this was called by the Israelis," she said in a video press conference with UN reporters.
"They said they would wait 48 hours. That was on Friday morning, I believe, until Sunday morning, and that they were going to evaluate."
The UN official said they were surprised when Israeli warplanes sent more than 100 tons of bombs crashing down on key security installations in Gaza starting Saturday morning.
"There was only one rocket that went out on Friday, so it was obvious that Hamas was trying, again, to observe that truce to get this back under control."
The UN official said the general impression was that Hamas was not the party to violate the six-month truce that expired less than two weeks ago,
"I don't think they think the truce was violated first by Hamas," she said.
"I think they saw that Hamas had observed the truce quite strictly for almost six months, certainly for four of the six months, and that they got nothing in turn - because there was to be kind of a deal," Abu Zayd explained.
"If there were no rockets, the crossings would be opened...The crossings were not opened at all.
Wednesday, December 31
Israel Kills More in "All-Out" Gaza War
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