Israeli warplanes have pounded Gaza, killing seven - including five Palestinians from the same family - as Hamas said it would support a Palestinian effort to investigate war crimes in the conflict.

The deadliest Israeli air strike on Saturday levelled a home in Al-Zawayda in central Gaza, killing a couple, their sons aged three and four, and a 45-year-old aunt, medics said.

Another seven Palestinians were wounded in an Israeli strike that struck a house in Zeitoun, east of Gaza City, medics said.

Witnesses and Palestinian officials said two mosques were destroyed in the Khan Yunis area of southern Gaza, while a third, in the Shati refugee camp, which had already been damaged, was bombed again.

The Israeli military said it had carried out about 20 air strikes over the Gaza Strip early on Saturday. Israeli officials said that more than 80 rockets were fired from Gaza on Friday.

Loud explosions and thick plumes of smoke could be seen over Gaza City on Saturday morning as fighting continued between Israel and Hamas, according to the AP news agency.

Earlier, there were conflicting reports regarding the death toll.

Hamas 'agrees' to join ICC

Eighty-one Palestinians and a four-year-old Israeli boy have been killed and nine Israeli civilians wounded since Tuesday, when truce talks collapsed ending nine days of calm.

Israel has vowed no let-up until it can guarantee the safety of its civilians, while Hamas insists that Israel must end its eight-year blockade of the territory as part of any truce.

Meanwhile, a senior Hamas leader who has been taking part in the Cairo negotiations has confirmed that the group will back any Palestinian bid to join the International Criminal Court (ICC).

According to Moussa Abu Marzouk, Hamas has signed a paper of support requested by the Palestinian President Mahmoud Abbas.

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Palestinians accuse Israel of war crimes in Gaza because of its attacks on civilians. If Palestine did join the ICC, it would mean Hamas could also be investigated.

Al Jazeera's Jane Ferguson, reporting from Gaza, said that both Hamas and Islamic Jihad expressed their willingness to throw their support behind President Mahmoud Abbas' bid to join the ICC.

"This is significant because they haven't vocally given any support. Simply because, to sign up for this you are potentially going to be investigated yourself. This potential membership of the ICC has aggravated Israel enormously," she said.

"Technically, the Palestinians could be able to claim or at least ask for a trial-led investigation into war crimes here, and this is especially sensitive since over 2,000 have already been killed here."

Protests in West Bank

In the occupied West Bank, Al Jazeera's Nida Ibrahim, reporting from Hebron, said that Hamas supporters clashed with Palestinian security forces while demonstrating against Israel's military offensive.

The Palestinian police fired stun grenades and tear gas to disperse protesters. Demonstrators accused the security forces of collaborating with the Israeli army. Clashes also took place in other West Bank cities of Bethlehem and Ramallah.

According to Palestinian health officials, at least 2,098 Palestinians have been killed since the fighting began on July 8. At least 10,540 have been reported injured.

According to the UN figures, at least 478 Palestinian children and minors were among the dead, including 320 who were 12 or younger.

On the Israeli side, the death on Friday of a four-year-old boy, who died when a mortar shell hit two cars in Nahal Oz, raised the death toll to 68, including 64 soldiers, three civilians and a Thai worker.

Source: Al Jazeera and agencies