At least 50 people were killed overnight in Israeli strikes, most of them in Rafah, raising the Palestinians death toll to 1650, mostly civilians, Gaza health officials said.
They said 8,900 Palestinians have been injured so far.
Massive Israeli artillery shelling yesterday killed 160 Palestinians across the Hamas-ruled Gaza Strip following the collapse of a 72-hour truce just two hours after it began.
Hamas, which rules the narrow coastal strip, today claimed responsibility for the incident but said it was carried out before the start of the ceasefire and it had not violated a US- and UN-sponsored humanitarian truce.
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Its armed wing - Ezzedine al-Qassam Brigades - said it had no information on the whereabouts of captured soldier and he might have been killed in massive Israeli shelling.
An Israeli army spokeswoman said 51 rockets and mortar rounds hit Israel yesterday, with another nine rockets shot down by the Iron Dome missile defence system.
So far, 63 Israeli soldiers, including two Indian-origin, have been killed in the conflict. Nearly 400 soldiers have been injured. Three Israeli civilians and a Thai national also died in rocket and mortar attacks.
Israeli forces shot dead two Palestinians during separate clashes in the northern and central West Bank yesterday.
The Palestinian toll in the ongoing Israeli assault on Gaza has surpassed that of Operation Cast Lead in 2008-2009 as the conflict entered its 26th day today.
"I think it's going to be very hard to put a ceasefire back together again if Israelis and the international community can't feel confident that Hamas can follow through on a ceasefire commitment," Obama told reporters yesterday.
The US also blamed Hamas for the breakdown of the truce, saying the "barbaric" attack by the Palestinian militant group was an "outrageous violation" of the ceasefire.
Meanwhile, Egypt has decided to open the Rafah border crossing exceptionally to receive injured Palestinians.