Gordon Brown will offer an olive branch to President Bush tonight by describing the United States as Britain’s most important ally and central to his foreign policy plans.

Mr Brown’s remarks, in a speech at the Lord Mayor’s Banquet at Guildhall, will be seen as an attempt to mend fences with the White House after a series of diplomatic tensions.

Unlike Tony Blair, whose close relationship with President Bush earned him the tag “poodle”, the Prime Minister has placed less emphasis on personal relations and instead emphasised the values and historic ties shared by Britain and America.

Tensions have also arisen over his appointment to the Government of Lord Malloch-Brown, a critic of the Iraq war and neo-conservatism, and comments by Douglas Alexander, the International Development Secretary, seen as coded criticisms of the US’s unilateralist foreign policy.

Mr Brown will use his speech tonight to spell out the importance of the US to achieving his own foreign policy goals of strengthening the UN and other global bodies.

His tentative steps to distance himself from President Bush have coincided with moves by President Sarkozy of France and Chancellor Merkel of Germany to rebuild links with the US after their own countries opposed the invasion of Iraq in 2003.

But Mr Brown will argue that, rather than threatening to rival Britain’s relationship with the US, the new pro-American thrust of French and Germany diplomacy presents an opportunity that must be seized.

In an interview with Sky News yesterday, Mr Brown said: “America is our most important ally, it will always be because of the values we share with America, and so it is central to how we conduct our foreign policy. The great change that is taking place, that I think is to the advantage of everyone, is that France and Germany and the EU are also moving more closely with America. And I think that’s to the benefit of Britain, it’s to the benefit of the world.”

Britain, France and Germany have previously worked together to seek a diplomatic solution to attempts to stop Iran from developing a nuclear weapons programme, although Mr Brown said that diplomacy must be stepped up again and refused to rule out military action, as he has throughout.

Mr Brown is also keen to seek agreement for reforms to the UN and its agencies, whose authority was damaged when America and Britain invaded Iraq without its authority, and the International Monetary Fund and World Bank. “There’s a great opportunity for all of us to work together to reshape the international institutions, to make them fit for purpose for the decade that we are in,” he said.

Lord Malloch-Brown fought back against a series of media attacks. The former UN deputy Secretary General spoke of his dismay at criticism of his decision to move into a grace-and-favour flat in Admiralty House and admitted that he had been unprepared for the rough and tumble of British politics, but denied speculation that he might quit his new post.

“I feel a bit like the bewildered Dr Who figure who stepped out of the Tardis. Press and political relations have been made into a contact sport. I am the first to acknowledge that I was clearly not prepared for that,” Lord Malloch Brown told The Observer.

He admitted to a diplomatic error by suggesting in the House of Lords that Britain might open negotiations with Hamas and Hezbollah, which he was forced to retract.

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