Tackling the crisis in the Middle East will be the "first and most immediate" issue for incoming US President Barack Obama, Gordon Brown said today.
The Prime Minister said he hoped to work "very closely" with Mr Obama after he officially takes office on January 20.
And he predicted that Britain's relationship with the US would "strengthen over the years" with the new President at the helm.
As Israel's offensive in Gaza continued for a 19th day, Labour former minister Nigel Griffiths (Edinburgh S) asked Mr Brown if he would work with the incoming President to secure a "lasting peace" in the region
He said: "Will you send best wishes to President-elect Obama for his inauguration next Tuesday and will you work with him to secure lasting peace in the Middle East?"
The Prime Minister replied: "I have had the advantage of talking to President Obama about some of these issues.
"I think the whole House will want to welcome the new President when he comes in. We hope to work very closely with him.
"There are major international issues, the first and most immediate is the Middle East, and I believe the relationships between Britain and America will strengthen over the years."
Labour's Jeremy Corbyn (Islington N) earlier accused Israel of committing war crimes and urged Mr Brown to join calls to refer the country to the International Criminal Court.
Mr Corbyn said: "The Israeli forces in the past three weeks have killed 1,000 people in Gaza, 300 of whom are children; denied medical aid; denied food; denied energy and blockaded the people during the last year.
"These are war crimes, they have committed acts against the people of Gaza that ought to be referred to the International Criminal Court.
"Will you join calls to ensure that takes place?"
Mr Brown said "words cannot describe" how families would feel at the human cost of the conflict in Gaza but the international community was doing "everything we can" to secure a ceasefire.
The Prime Minister told MPs: "We took action in drafting the resolution that went through the United Nations last week and words cannot describe the feeling that families will have as a child dies or at the level of civilian deaths and casualties, and the displacement of 90,000 people in Gaza.
"But what our resolution sought to do was to call for an immediate ceasefire, to recognise the damage that had been done and was being done, call for humanitarian action - something I repeated when I talked to (Israeli) prime minister (Ehud) Olmert and asked for humanitarian access to be increased last night - and then to take the action that is necessary to achieve a ceasefire."
He said the UN resolution had been backed because Arab countries were also prepared to take steps to end arms trafficking to Palestinian militants and to open border crossings.
The Prime Minister added: "It is important that we have the Arab League countries as well as the other countries who signed that motion in support of us.
"In other words we are doing everything we can to make possible an immediate ceasefire."
Mr Brown later said he was also looking forward to working with President Obama on measures to help fix the world's economies, arguing that coordinated action would increase benefits in the UK.
And he paid tribute to President George W Bush for being "the first to realise" the importance of fighting international terrorism.
This followed a question from Democratic Unionist Gregory Campbell (Londonderry E), who provoked laughter across the House when he asked: "Next week the new President of the United States of America takes office. What other differences are there between you, apart from you inadvertently saying that you have already saved the world and the President saying that he needs to?"
Mr Brown replied: "I'm looking forward to working with President Obama. Let me also pay tribute to what President Bush has done - because he was the first to realise the importance of dealing with international terrorism after September 11, 2001.
"But a new administration has policies for a fiscal stimulus that will help Northern Ireland as well as the rest of the United Kingdom.
"If all the economies can work together in coordination then the benefit of what we do individually can be magnified a great deal.
"I believe that the work that the Obama administration is about to do to build a stronger economy will be complemented by what we can do in Europe, what China and other countries can do."Reuse content