Israel widened its air assault against the Gaza Strip's Hamas rulers on Saturday, hitting a mosque, Hamas-affiliated charities and an Islamic home for the disabled, as Palestinians said the death toll from the five-day offensive rose to 135.

While Israel vowed to press forward with its five-day-old campaign, it found itself facing growing international calls to stop. In New York, the UN security council unanimously called for a ceasefire, while Britain's foreign minister, William Hague, said he would be discussing ceasefire efforts with his American, French and German counterparts on Sunday.

The 15-member security council issued a press statement calling for a de-escalation, restoration of calm and a resumption of the Middle East peace talks. The press statement, which is not legally binding but reflects international opinion, was the first response by the UN's most powerful body.

An Israeli official said the goal of the operation is to restore quiet to Israel for a continuous period. "This goal will be achieved whether it is done militarily or diplomatically. Israel will consider any suggestion that will bring the accomplishment of this goal," the official said.

The military said it has struck more than 1,100 targets, including Hamas rocket launchers, command centres and weapon manufacturing and storage facilities, in a bid to stop relentless rocket fire coming Gaza. Officials in the territory said that two women were killed in the attack on the disabled centre.

The central Gaza mosque was being used to conceal rockets like those militants have fired nearly 700 times toward Israel over the past five days, the military said. However, the strikes in the densely populated Gaza Strip show the challenge Israel faces as it considers a ground operation that could potentially pose further dangers to civilians.

Gaza health ministry spokesman Ashraf al-Kidra said Israeli strikes raised the death toll there to 135, with more than 920 wounded. Among the dead was a nephew of Ismail Haniyeh, a top Hamas leader, who was killed in an airstrike near his home, Hamas officials said.

Hamas militants have been hit hard. Though the exact breakdown of casualties remains unclear, dozens of the dead also have been civilians. Israel has also demolished dozens of homes it says are used by Hamas for military purposes.

"Am I a terrorist? Do I make rockets and artillery?" screamed Umm Omar, a woman in the southern town of Rafah whose home was destroyed in an airstrike. It was not immediately known why the building was targeted.

The offensive showed no signs of slowing down Saturday as Israeli defence minister. Moshe Yaalon, said his country should ready itself for several more days of fighting.

"We have accumulated achievements as far as the price Hamas is paying and we are continuing to destroy significant targets of it and other terror organisations," Yaalon said after a meeting with top security officials. "We will continue to punish it until quiet and security returns to southern Israel and the rest of the country."

Hamas said it hoped the mosque attack would galvanise support for it in the Muslim world.

"(It) shows how barbaric this enemy is and how much it is hostile to Islam," said Husam Badran, a Hamas spokesman in Doha, Qatar. "This terrorism gives us the right to broaden our response to deter this occupier."

The Israeli military released an aerial photo of the mosque it hit, saying Hamas hid rockets in it right next to another religious site and civilian homes. It said Hamas, Islamic Jihad and other Gaza militant groups use religious sites to conceal weapons and establish underground tunnel networks, deliberately endangering civilians.

Critics say such allegations are too sweeping, and that Israel's heavy bombardment of one of the densely populated territories is itself the main factor putting civilians at risk.

Sarit Michaeli of the Israeli human rights group B'Tselem said that while using human shields violates international humanitarian law, "this does not give Israel the excuse to violate international humanitarian law as well."

Israel issues early warnings before attacking many Gaza targets and the military says it uses other means to do its utmost to avoid harming bystanders. But Michaeli said civilians have been killed when Israel bombed family homes of Hamas militants or when residents were unable to leave their homes quickly enough following the Israeli warnings.

The "Iron Dome," a US-funded, Israel-developed rocket defence system, has intercepted more than 130 incoming rockets, preventing any Israeli fatalities so far. A handful of Israelis have been wounded by rockets that slipped through.

Militant rockets have reached further into Israel than ever before, with air raid sirens sounding even in the northern city of Haifa, 100 miles (160 kilometers) away.

In London, Hague said he had spoken to his Israeli counterpart and called for an "immediate de-escalation" and expressed his "deep concern" about civilian casualties.

He called for "urgent, concerted international action to secure a ceasefire" and said he would discuss that goal with his American, French and German counterparts in Vienna on Sunday.

The Arab League said foreign ministers from member states will hold an emergency meeting in Cairo on Monday evening to discuss the continued Israeli offensive and measures to urge the international community to pressure Israel.

Egypt, which historically has served as a mediator between Israel and Hamas, appears less eager to help out this time. Hamas was particularly close to the Muslim Brotherhood, who the current leadership banned after driving it from power last year.

Still, it has tried to show support for Palestinians by opening its crossing with Gaza, allowing deliveries of food and medical supplies and evacuation of some wounded.