Israel has launched a third day of air strikes on Gaza as the death toll from the wave attacks passed the 300 mark.
More than 300 bombing raids since Saturday have wreaked devastation, killing 315 people including civilians and children.
Most of those killed are reported to be members of Hamas security forces but the United Nations agency responsible for Palestinian refugees said at least 51 of the dead were civilians.
The attacks have left more than 1,400 wounded, overwhelming hospitals and exacerbating shortages of fuel, food and medicines.
Israel’s Cabinet has now approved a call-up of 6,500 reserve soldiers in apparent preparation for a ground offensive.
The country has also doubled the number of troops on the Gaza border since Saturday and also deployed an artillery battery.
It is not clear, however, whether the deployment is meant to pressure Hamas or part of a planned ground assault.
Israel has insisted it will keep up the assault until militants stop launching rockets, with defence minister Ehud Barack warning ominously that “the time has come to fight” and signalling willingness to put “boots on the ground”.
Palestinian chief negotiator Saeb Erekat said: “What Israel is doing deserves the strongest condemnation of the international community.
“At the end of the day you don’t solve such problems with military means and such large-scale attacks have led to the killing of 300 people, 1,000 wounded, the total destruction of infrastructure.
“This will add to the complexity, this will enlarge the cycle of violence and counter-violence and this will really undermine the peace process, or what is left of it.”
Britain has joined international calls for an immediate halt to the violence in the region.
Foreign Secretary David Miliband said an “urgent ceasefire” was needed to stop “massive loss of life” in the territory.
He insisted that Tel Aviv must abide by its “humanitarian obligations” and Prime Minister Gordon Brown shared his “grave concern” over the situation.
“The Prime Minister and I are following developments in Gaza with grave concern,” said Mr Miliband.
“The rise in rocket attacks on Israel since December 19, and yesterday’s massive loss of life, make this a dangerous moment which should be of concern to the whole of the international community. The UK supports an urgent ceasefire and immediate halt to all violence.”
