Gordon Brown will use a keynote foreign policy speech later to argue the global financial crisis has given world leaders a major opportunity for change, reported BBC.
The PM, in his annual speech at the Lord Mayor's Banquet in London, is expected to call for the rebuilding of the international financial system.
He will urge countries to forge a new way of working together that is "hard headed and progressive".
His speech will also be watched for any suggestions of possible UK tax cuts.
Mr Brown's comments in recent days about the need for a fiscal stimulus to boost the domestic economy have given rise to mounting speculation about possible moves in that direction.
Ahead of a meeting of leaders of the world's 20 major economies in the US at the weekend, Mr Brown is expected to say that recent co-ordinated global action during the credit crisis showed the potential of a stronger multilateralism.
He will argue that 2008 should not be remembered just for the failure represented by the financial problems, but for the way countries reacted and "discovered and refashioned the global power of nations working together".
"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," Mr Brown will say, according to pre-released extracts of his speech.
The UK, the US and Europe are key to establishing a new world order, he will argue.
A new financial system "based on the principles of transparency, integrity, responsibility, sound banking practice and global governance with co-ordination across borders", is also needed, he will say.
This would involve "an early warning system and a crisis prevention mechanism for the whole world", he will add.
As well as strengthening the global economy, Mr Brown will set out another four challenges the world faces - the promotion of democracy, the fight against terrorism, climate change and the resolution of conflicts.
Meanwhile, government sources signalled over the weekend that some form of targeted help for those in the UK worst hit by the downturn was under consideration - although they said no decisions had yet been taken.
The Tories unveil their own plans, aimed at dealing specifically with unemployment, on Tuesday.
They say they would fund tax cuts through existing spending and not - as they suspect the government would do - through borrowing.