Tony Blair says an immediate ceasefire is possible if firm action is taken
The conflict between Israel and Hamas can be resolved, former UK prime minister Tony Blair has insisted.
Mr Blair, now a Middle East envoy, said there was a "basis" for an immediate ceasefire if the supply of arms into Gaza from Egypt was halted.
Israeli forces continue to widen their attacks in Gaza while at least 40 people have reportedly been killed in an air strike on a UN-run school there.
The Foreign Office said it was doing everything possible to get a ceasefire.
Foreign Secretary David Miliband is on his way to New York for talks on the crisis at the United Nations.
The UK was "pushing every diplomatic and political lever" in an attempt to broker a halt to hostilities, Foreign Office minister Bill Rammell told the BBC.
Mr Rammell said the escalation of the conflict in recent days had caused "alarm and dismay" around the world.
According to Palestinian medical officials, up to 600 people have been killed since the conflict began.
At least 70 Palestinians and five Israeli soldiers were killed on Tuesday.
Mr Blair said the people of Gaza were living through "hell" and warned of an even "more protracted campaign" if opportunities were not seized to end the violence.
Mr Blair, who represents the UN, EU, US and Russia in the Middle East, said he believed discussions between Egypt and Hamas about halting the supply of arms and money to militants in Gaza were critical to securing a ceasefire.
There needed to be "clear, definitive" action to bring this about, Mr Blair said, adding that he thought all sides were willing to discuss this.
"I think there are circumstances where we can get an immediate ceasefire and that is what people want to see," he told the BBC.
Israel has insisted circumstances are not right for a ceasefire while rocket attacks continue to strike its territory.
Mr Blair, who has met Israeli leaders and senior Palestinian officials in recent days, called on Hamas to work towards a ceasefire to end the "appalling suffering" in Gaza.
"If they truly do care about about people in Gaza, there is a possible way that would have an immediate cessation of hostilities and that is obviously what any responsible person should try and achieve.
"For anyone living in Gaza, it is hell. It is bound to be. You are have got a situation where you are in an effective war zone."
Only a "credible" political process towards a Palestinian state could bring peace to the region, Mr Blair said, stressing that "real change" in conditions for people in Gaza were part and parcel of this.
Discussions between the international community and Hamas were feasible, he said, but only if there were "some common principles of agreement", namely Hamas' willingness to give up violence.
He urged the new US administration of President-elect Barack Obama to focus on the Middle East peace process, saying the issue was "absolutely central" to global security.
"If we want to resolve this, we can," he said.
"We have to grip it and sort it. If we do that with requisite dedication energy and commitment, we can resolve it."