Foreign Secretary Philip Hammond has welcomed the news of a 72-hour ceasefire in Gaza, but stressed the need to “redouble efforts” to bring about a lasting solution.
The news was also hailed by former prime minister Tony Blair, who said there must be a “new and hopeful future for both sides”.
A statement announcing the three-day humanitarian ceasefire was released in New Delhi where US secretary of state John Kerry is meeting Indian officials.
A joint statement by America and the UN said they had received assurances that all parties to the conflict had agreed to an unconditional ceasefire during which there would be negotiations on a more durable truce.
In a separate statement, Mr Hammond called the news “an achievement we have all been working tirelessly for”, adding: “I applaud the efforts of secretary Kerry and partners such as Egypt who should be congratulated for all they have done to bring an end to this humanitarian crisis.”
But he added: “We should now redouble our efforts and leave no stone unturned, to ensure this is a lasting and durable ceasefire to make way for substantial discussions to resolve the underlying issues on both sides.”
Speaking at a Labour Party Eid event before the ceasefire announcement, party leader Ed Miliband called the deaths of civilians, women and children “horrific” and “appalling”.
He added: “As ever, it is the civilian population that is suffering most from this conflict … and as a husband and father watching the news and heartbreaking images, we have seen, has become almost unbearable.
“I speak as a friend of the Israeli people and the Palestinians. The murder of the three Israeli teenagers at the start of this recent cycle of violence was an appalling and brutal act.
“And the rocket attacks by Hamas from Gaza are unjustifiable, outrageous and an act of terror. So of course, I defend Israel’s right to defend itself and its people against these attacks.
“But I simply cannot justify what we are seeing unfolding in Gaza. A mounting death toll of innocent Palestinian civilians. One in four of them children and in the past few days we have seen two UN schools bombed killing many Palestinian children simply taking shelter from the bombardment.
“I have said very clearly – the Israeli incursion into Gaza is wrong and unjustifiable.
“It is wrong because, despite the extreme provocation from Hamas, it has led to the killing of so many innocent men, women and children, because it will fail to act as a deterrent or as a solution to the rocket attacks and because it risks leading to the recruitment of a new generation of Palestinians to the cause of Hamas.
“People across the world are asking how many more children will die before a cessation of violence is achieved?
“We must renew our long standing commitment to seeking a two state solution with bothIsrael and Palestine living alongside each other in peace and security because there can be neither dignity for the Palestinian people nor security for Israel without it.
“Let us resolve today that we must do everything in our power to prevent future Eids being marked by this violence and killing.”
Mr Blair – Middle East envoy for the quartet of the United Nations, EU, US and Russia – said the ceasefire gave the sides the opportunity to reach a “sustainable arrangement that will address Israel’s security concerns, as well as ensure a better future for Gazans”.
He said: “Too many innocent lives have been lost in Gaza, and lives left in ruins. In order to give some hope back to the people of Gaza, its people have to see an end to the terrible loss of life, the destruction and the isolation from the world.
“The Palestinian Authority – as the proper authority in Gaza – will play a vital role in its reconstruction and redevelopment, helping to reunite Gaza and the West Bank.
“After all the misery and suffering of the past weeks, there cannot be a return to the status quo ante. Israelis need to know that they have genuine protection from rockets, tunnels and terror attacks.
“There must be a new and hopeful future for both sides. It is to that end we should work – and the international community is committed to implementing a durable arrangement.
“A longer term strategy will also give the sides an opportunity to create a political momentum, and lead to the renewal of the negotiations for a two-state solution.”
Earlier, it emerged that two Conservative MPs have written to the Government expressing their concern over the situation in Gaza.
In a letter to Mr Hammond, Margot James (Stourbridge), who is now working with William Hague, said her constituents regarded the Israeli action as “wholly disproportionate to the threat posed by Hamas”.