Gordon Brown will say tonight that the time is right to create a "truly global society" following the election of Barack Obama in the US.

The Prime Minister will use his annual Mansion House foreign policy address to call on global leaders to forge a "new multilateralism" and "seize the moment" presented by the financial crash which has engulfed the world.

Adopting some of the more elevated language used at the election of President Obama, Mr Brown will say that "America stands at its own dawn of hope." But in a shot across the Atlantic at the President-elect, Mr Brown will urge the rejection of "beggar-thy-neighbour protectionism that has been a feature in transforming past crises into deep recessions".

Although Downing Street believes it has got the green light from Mr Obama to revive the negotiations over the Doha round of the World Trade Talks, the Democrat repeatedly expressed caution during his campaign over free trade. He said on a number of occasions that trade agreements should "not just be good for Wall Street, it should also be good for Main Street" and stressed that any agreements must improve working conditions around the globe.

Mr Brown will hope that his speech builds on his role as "global Chancellor of the Exchequer" which was formed during the financial crisis, as Britain led the way with the solution to the banking bailout. The Prime Minister is one of at least 20 world leaders meeting in Washington at the invitation of President Bush to discuss reform of global financial institutions and the regulation of financial markets.

Mr Brown will say tonight: “Uniquely in this global age, it is now in our power to come together so that 2008 is remembered not just for the failure of a financial crash that engulfed the world but for the resilience and optimism with which we faced the storm, endured it and prevailed. And remembered too for how in doing so we discovered and refashioned the global power of nations working together .

“And having shown the power of coordinated global action to recapitalise our banks and cut interest rates for homeowners and businesses, this weekend in Washington we will seek to go further, launching the process of rebuilding the international financial system.

“So while I see a world that is facing financial crisis and still diminished by conflict and injustice I also see the chance to forge a new multilateralism that is both hard headed and progressive. And if we learn from our experience of turning unity of purpose into unity of action, we can together seize this moment of change in our world to create a truly global society.”

Downing Street has played down the chances of a far-reaching deal being agreed next Saturday at the meetings, suggesting that it will mark the start of a process. Finance ministers, including Stephen Timms, the Financial Secretary to the Treasury, met in Sao Paulo on Saturday to discuss the agenda for next weekend.

Robert Zoellick, the President of the World Bank who attended the meetings, said after the meeting "it's too early to say" what progress was made toward establishing a new system. He warned that divisions between the major players were still holding back progress. "I think this is one of those fluid periods where people are trying to get a sense of the right mix of countries and institutions to be able to solve problems in a way that is effective but also legitimate," he said.

Mr Zoellick added that "there are certainly countries jockeying for position" but noted that "there is a clear recognitiion about various steps to improve financial regulation and supervision."

President Sarkozy has been pushing for greater regulation of the financial markets to be embraced by world leaders on Saturday, but Britain has been more cautious. However tonight Mr Brown will urge all sides to put aside differences and call on both the Europe and the US need to work more closer together.

He will say: “The alliance between Britain and the US - and more broadly between Europe and the US - can and must provide leadership, not in order to make the rules ourselves, but to lead the global effort to build a stronger and more just international order. The transatlantic relationship has been the engine of effective multilateralism for the past 50 years.

“As America stands at its own dawn of hope, so let that hope be fulfilled through a pact with the wider world to lead and shape the twenty-first century as the century of a truly global society. And I believe the whole of Europe can work closely with America to meet the great challenges which will test our resolution and illuminate our convictions.”

Mr Brown will set out the five great challenges the world now faces: the need to reassert faith in democracy and win the battle of ideas against terrorism and extremism; the need to strengthen the global economy; tackling climate change; resolving conflict and the need for a new stabilisation and reconstruction agency ready, through civilian as well as military assistance, to rebuild conflict-ridden and fragile states; and meeting the Millennium Development Goals.

He will conclude with an appeal to world leaders: “My message is that we must be: internationalist not protectionist; interventionist not neutral; progressive not reactive; and forward looking not frozen by events. We can seize the moment and in doing so build a truly global society.”

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