Israel pressed on with a punishing Gaza offensive and Hamas fired more rockets into the Jewish state Saturday in a two-week-old war that defied international efforts to stop it.

Medical officials in the Gaza Strip said the Palestinian death toll had risen to 786. Gaza's Islamist Hamas rulers said more than a third were children. Ten Israeli soldiers have been killed, as well as three civilians hit by Hamas rocket fire.

The Israeli military said 15 Hamas militants were killed in a series of 40 air strikes early Saturday that targeted rocket launch sites, tunnels used to smuggle weapons, weapons caches and production facilities.

Palestinian medics said two militants were killed, and one Israeli attack struck the outer wall of a hospital, wounding one worker.

Israeli bombings of tunnels on the border with Egypt knocked out electricity in the town of Rafah, residents said.

Hamas fired at least 30 rockets across the border at Israel Friday and at least another two Saturday. No casualties or damage were caused by Saturday's rocket attacks.

Israeli Prime Minister Ehud Olmert dismissed as "unworkable" a U.N. Security Council resolution demanding an "immediate and durable" ceasefire.

Hamas officials in the Gaza Strip said they were weighing the resolution but objected they had not been consulted. The group said it had sent three of its leaders from Gaza to Cairo to discuss a separate Egyptian ceasefire proposal.

Diplomats said Israel and Egypt were far apart on the plan.

In a telephone call to Olmert, UN Secretary-General Ban Ki-moon "expressed disappointment that the violence is continuing on the ground in disregard" of the Security Council resolution, U.N. spokeswoman Michele Montas said.

UN officials have no direct contacts with Hamas but Montas said the same message would be conveyed to the group indirectly.

On Friday, Israel's security cabinet debated for the second time in three days whether to send in reservists for a push into Gaza's towns and cities. There was no word on the outcome.

"I can't go into operational details. The military pressure on Hamas will continue," said Mark Regev, a spokesman for Olmert.

The U.N. Relief and Works Agency, which distributes much of the aid in Gaza, kept some of its operations suspended Friday after the death of one of its drivers in Israel's offensive.

U.N. aid workers planned to resume their movements in Gaza's rubble-strewn streets as soon as possible after receiving Israeli assurances that they were not being targeted, a U.N. spokeswoman said in New York.

US backing

The United States, which abstained in the UN vote, offered further public support for Israel's military goals.

"This situation will not improve until Hamas stops lobbing rockets into Israel," White House spokesman Scott Stanzel said.

He said President George W. Bush had voiced his concern to Olmert about the humanitarian situation and the loss of civilian lives during the Israeli assault on the Gaza Strip.

With the Palestinian civilian death toll already in the hundreds, Israeli actions have drawn denunciations from the Red Cross, U.N. agencies and Arab and European governments.

Hamas wants any ceasefire deal to include the ending of Israel's crippling economic blockade of the Gaza Strip and the withdrawal of all Israeli forces from the territory.

Israel's key demands are for a complete halt to Hamas rocket fire and for international guarantees to stop the group rearming via smuggling tunnels under the border with Egypt.

Regev said talks with Egypt over the ceasefire proposal would continue, but he did not say when.

The Egyptian initiative, also sponsored by French President Nicolas Sarkozy, may be in trouble, however.

"There is a growing sense that the Egyptian-French plan is not going to work," a senior European diplomat told Reuters.