Israel on Saturday approved a four-hour extension of a temporary truce in Gaza, Israeli television said, after the Palestinian death toll topped 1,000 with the retrieval of more than 130 bodies.

Channel 10 said the security cabinet had agreed to prolong a 12-hour truce that went into effect on Saturday morning by four hours, extending it until midnight local time (2100 GMT).

Shortly after the original truce expired at 1700 GMT, the Israeli military reported three mortar rounds fired from Gaza, but media reports said the army did not regard this as a major violation.

The truce extension decision came after US Secretary of State John Kerry and foreign ministers from Europe and the Middle East urged Israel and the Hamas movement to extend the fragile truce.

"We all call on parties to extend the humanitarian ceasefire," France's Foreign Minister Laurent Fabius told reporters in Paris after meeting Kerry and foreign ministers from Britain, Germany, Italy, Qatar and Turkey, as well as an EU representative.

"We all want to obtain a lasting ceasefire as quickly as possible that addresses both Israeli requirements in terms of security and Palestinian requirements in terms of socio-economic development."

There was no immediate response from Hamas to either that call or to the Israeli cabinet decision.

A spokesman for the UN chief said in a statement Ban Ki-moon "urgently appeals once again to all parties to declare a seven-day humanitarian ceasefire in Gaza as a prelude to renewing a political process as the only way of achieving a durable peace".

After the 12-hour ceasefire started at 0500 GMT, medics digging through the remains of hundreds of Gaza homes uncovered more than 130 bodies.

The grim discoveries pushed the Palestinian toll in Gaza to more than 1,000 since the conflict erupted on July 8.

Israel also announced the deaths of three more soldiers, raising its military toll to 40, along with two Israeli civilians and a Thai worker killed in Israel.

On the ground, Palestinian ambulances sped into Gaza neighbourhoods that have been too dangerous to enter for days.

Nine hours into the truce, they had found the bodies of more than 130 people in the debris.

Palestinians ventured onto Gaza's streets after the truce began, some eager to check homes they had fled, others to stock up on supplies.

In many places they found astonishing devastation: buildings levelled, entire blocks of homes completely wiped out by Israeli bombardment.

In northern Beit Hanun, even the hospital was badly damaged by shelling, and AFP correspondents came across the charred body of a paramedic.

There were similar scenes in Shejaiya, where stiff bodies lay on the floor of a room in one building, one caked in dried blood, all of them covered in dust.

East of southern Khan Yunis, residents hesitated to enter the Khuzaa neighbourhood, saying Israeli forces remained inside the border area.

And in nearby Bani Suheila, where 20 people were killed in a single Israeli air strike shortly before the truce began, women and children wept as they discovered their homes destroyed.

Hamas and Israel agreed to the "humanitarian window" early on Saturday, after Israel's security cabinet on Friday night rejected a US proposal for a seven-day truce during which the two sides would negotiate a longer-term deal.

Speaking after the rejection, at a news conference in Cairo with UN chief Ban, Kerry said Israel and Hamas "still have some terminology" to agree to on a ceasefire, but added they had "fundamental framework" on a truce.

The two sides remain at odds over the shape of a final deal to end the fighting, however.

Hamas says any truce must include a guaranteed end to Israel's eight-year blockade of Gaza, while in Israel there are calls for any deal to include the demilitarisation of the Gaza Strip.

The situation in Gaza has created tensions in the West Bank, where protests against Israel's role in the conflict erupted after Friday prayers.

Troops shot dead two Palestinian teenagers early Saturday in separate clashes in the north and south of the West Bank.

That followed the deaths of six Palestinians on Friday -- five shot dead by Israeli troops and one killed by an Israeli settler.

International concern has mounted over the civilian toll in Gaza, including over a Thursday attack in which at least 15 people were killed in alleged Israeli shelling of a UN school.

Rights groups say about 80 percent of the casualties have been civilians, and the UN agency for children UNICEF said on Friday that 192 children had been killed during the conflict.

The Israeli army announced three soldiers were killed in Gaza Saturday morning before the truce began.

Rocket fire from Gaza continued before the truce, with three shot down by anti-missile defences and one hitting open ground, the army said.