Cameron rejects Warsi criticism over Gaza
David Cameron has defended government policy on Gaza after outgoing Foreign Office minister Baroness Warsi called it "morally indefensible".
The prime minister said he had been "consistently clear" in calls for peace, adding that he agreed the crisis in the region was "intolerable".
Lady Warsi resigned on Tuesday morning, arguing that the government was not doing enough to alter Israel's actions.
She said she had tried without success to shift the government's position.
Deputy Prime Minister Nick Clegg said Israel had "overstepped the mark" in the conflict and called for the suspension of arms export licences.
The Liberal Democrat leader said an announcement would be made "very shortly".
Israel launched Operation Protective Edge in July with the stated aim of ending rocket attacks and destroying tunnels used by Palestinian militants. Gaza officials say the four-week conflict has killed 1,800 Palestinians and some 67 Israelis have also died.
But the two sides have agreed a 72-hour ceasefire, which came into force at 08:00 local time (05:00 GMT) on Tuesday.
Lady Warsi, the first Muslim woman to serve in a British cabinet, announced a few hours later that she was leaving the government with "great regret", but insisted she could "no longer support" government policy on Gaza.
Speaking to BBC News, she said: "Over the last four weeks I have done everything that I can, both at formal meetings and informal meetings, to try to convince my colleagues that our current policy on Gaza is morally indefensible, that it's not in our interests, it's not in British interests and that it will have consequences, both internationally and here at home.
"But, in the end, I felt the government's position wasn't moving and therefore I had to, on a point of principle, resign."
She later told Channel 4 News: "These issues are far too serious for us to have been mealy-mouthed and for us to be dragging our heels."
There is "unease" among Conservative backbenchers and "concern" at ministerial level over the government's position on Gaza, she said, adding: "I've had a minister in a late-night conservation talking about resignation."
Her resignation letter said government policy was "morally indefensible, is not in Britain's national interest and will have a long-term effect on our reputation internationally and domestically".
Lady Warsi went on to say that "I must be able to live with myself for the decisions I took or the decisions I supported. By staying in government at this time I do not feel that I can be sure of that."
Her decision followed criticism from several Conservative MPs that Israel's response to rocket attacks by Hamas militants in the West Bank and Gaza had been "disproportionate", a sentiment echoed on Tuesday by London Mayor Boris Johnson.
Mr Cameron has been accused of not reacting robustly enough to Israel's actions.
In his response to Lady Warsi's resignation, he wrote that he was "sorry" to see Lady Warsi, once one of his staunchest supporters, leave government.
He added: "I realise that this must not have been an easy decision for you to make and very much regret that we were not able to speak about your decision beforehand."
The prime minister continued: "I understand your strength of feeling on the current crisis in the Middle East - the situation in Gaza is intolerable.
"Our policy has always been consistently clear: we support a negotiated two state solution as the only way to resolve this conflict once and for all and to allow Israelis and Palestinians to live safely in peace."
Analysis by BBC Political Correspondent Robin Brant
There is no evidence that Mr Cameron is changing his mind or re-assessing the government's stance on Israel's conduct during this war.
The prime minister has faced criticism from some in his own party for not condemning Israel for what they believe is its disproportionate use of force against Hamas and civilians in Gaza.
He described an attack on Monday as a "slaughter" and said the situation was "intolerable". Other senior ministers have called it a "catastrophe".
But neither Mr Cameron nor any Conservative minister has said that Israel has gone beyond what is proportionate. The response on Tuesday afternoon from the new foreign secretary, Philip Hammond, was telling.
What Lady Warsi has labelled a "morally indefensible" position he has dismissed as a call for "megaphone diplomacy". He emphasised that he felt he had to be "balanced".
Mr Clegg said he shared Lady Warsi's concerns about arms export licences.
He said: "It's obvious to me, that however much Israel has every right to defend itself from rocket attacks from Hamas, nonetheless the Israeli military operation overstepped the mark in Gaza - this outrageous spectacle of these three UN schools being hit by the Israeli military action - and that's why I believe that the export licences should now be suspended."
He said he had been working with Lib Dem Business Secretary Vince Cable to get the suspension finalised.
Labour leader Ed Miliband told the BBC: "The government's position is wrong and I think Sayeeda Warsi's statement is completely right about this."
He said that Mr Cameron had to "think much more clearly" about policy on Gaza and had to "break his silence" over Israel's actions.
But Foreign Secretary Philip Hammond said: "I do find it rather surprising that she has chosen now, this particular moment, to take this step when, in fact, we are now at long last seeing some relief, seeing some progress on the issues about which she was so passionately concerned."
Downing Street said a review of export licences to Israel was under way, and no new military licences had been issued since the Israeli operation was launched.
A spokesman said: "Suspending export licences is not a decision we take lightly and it is right that we examine the facts fully. This is the approach being taken by the vast majority of countries.
"We welcome the current ceasefire and the withdrawal of Israeli troops from Gaza, and continue to call for a political solution to be found."
One of five daughters of Pakistani immigrants, Lady Warsi grew up in Dewsbury, West Yorkshire, studied law at Leeds University, working for the Crown Prosecution Service before setting up her own legal practice.
She was demoted from the Conservative chairman - a full cabinet post - to a middle-ranking Foreign Office post in 2012, being made minister for faith and communities at the same time.