Tony Blair has hailed the agreement of a draft United Nations resolution as "an absolutely vital first step" towards ending the conflict in Lebanon.
The draft resolution calls for a full cessation of hostilities but allows Israel to respond if attacked.
Mr Blair had been criticised over his handling of the crisis and delayed his holiday to help find a solution.
Foreign Secretary Margaret Beckett has gone on holiday to France but said she will be available to travel if needed.
Mr Blair said: "I welcome the tabling of this resolution.
"The priority now is to get the resolution adopted as soon as possible and then to work for a permanent ceasefire and achieve the conditions in Lebanon and Israel which will prevent a recurrence.
"Of course as I said yesterday we cannot and must not lose sight of the Palestinian dimension which is the root cause of this conflict.
"I will work tirelessly to re-energise the Middle East Peace Process which is the only way to provide a viable, long-term solution to this situation, with a Palestinian state alongside a secure Israel."
The British Ambassador to the UN, Emyr Jones-Parry, told BBC News 24 he hoped the resolution would be voted through as soon as Monday.
"In the last 48 hours the governments of France and the United States, acting really in direct contact with the parties in the region, have helped produce a text which I very much hope will do the job," he said.
The prime minister's comments came as a march involving thousands of people took place in central London calling for an immediate ceasefire in Lebanon.
The Stop The War Coalition asked people at the demonstration on Sunday to put children's shoes at the Cenotaph in protest at the deaths of children in the conflict.
March organisers said more than 100,000 people had attended the event, but police put the figure at about 20,000.
The prime minister had also been facing criticism from backbench Labour MPs, despite his decision to delay his summer holiday for a few days so he could focus his efforts on helping find a solution to the conflict.
Glasgow MP Mohammad Sarwar said the prime minister's policy had "lost credibility" in the country and joined other Labour MPs in urging the recall of Parliament.
Mr Sarwar said foreign diplomats, religious leaders and members of the public had voiced their concerns that Mr Blair was not doing enough.
''We believe that Israeli military actions are excessive, aggressive and disproportionate and our prime minister has failed to represent the county's feelings during this conflict," he told the BBC Radio 4 Today programme.
"He has refused to endorse Jack Straw's remarks that Israel's response is disproportionate... he has refused to call for an immediate ceasefire."