Israel and Hamas accused each other of violating the truce.

The ceasefire, announced by the US and the UN hours earlier, took effect at 3pm yesterday after heavy fighting that killed 17 Palestinians and five Israeli soldiers.

But the most recent victims, including two children, were killed by Israeli tank fire shortly after the deadline, a spokesman for the local emergency services said.

The deaths brought the toll on the Palestinian side to more than 1450 since the Israeli offensive in the Gaza Strip began on July 8.

Mediators were to meet in Cairo this weekend to try to find sufficient common ground between Israel and Hamas so the 72-hour ceasefire in Gaza can be made ­permanent.

The future of the talks is not clear but are believed to be in doubt. After much public and private pressure from the US following the shelling of a UN school in Gaza, Israel agreed to discuss an end to the 25-day war with Hamas.

Israeli media reported that after completing the task of destroying Hamas’s tunnel network in coming days Israeli forces would unilaterally withdraw from Gaza. Delegates from Israel and Hamas will attend talks this weekend in Cairo.

They will not meet directly but through mediators including the US, Egypt and the Palestinian Authority, the moderate faction from the West Bank.

Israeli officials are certain to push for a de-militarisation of the Gaza Strip, probably monitored by the Palestinian Authority, while Hamas will want a lifting of Israel’s seven-year blockade of the enclave. Israel is expected to agree to a partial easing of the blockade, to be monitored by the Palestinian Authority.

The ceasefire was always considered fragile. “It is a lull of opportunity,” US Secretary of State John Kerry said. “There are no guarantees, this is a difficult … issue.”

About 1443 Palestinians have been killed since the war began on July 8, and 8350 injured, according to Gaza’s Ministry of Health.

Most of the dead and injured were civilians.

On the Israeli side, 61 soldiers and three civilians were killed.

That total included five soldiers who were hit by a mortar on the ­Israeli side of the border only hours before the ceasefire began.

The ceasefire was announced shortly after the UN officer in charge of Gaza, Pierre Krahenbuhl, warned the population of Gaza was “facing a precipice”.

In a joint statement, Mr Kerry and UN Secretary-General Ban Ki-moon said: “We urge all parties to act with restraint until this ­humanitarian ceasefire begins and to fully abide by their commitments during the ceasefire.

Israel’s Prime Minister Benjamin Netanyahu had been under pressure from US President Barack Obama, who telephoned him to say Israel should hold its fire, and from hardliners in his cabinet who wanted a tougher operation.

The ceasefire announcement came hours after Mr Netanyahu had vowed to destroy Hamas’s tunnel network “with or without a ceasefire”. Israel says it has discovered about 30 tunnels which were designed with the intention of ­allowing attacks or kidnapping ­operations into Israel.