The United Nations must be reformed to allow it to "think sooner and act quicker" in defence of basic freedoms, Tony Blair said today.
In a major foreign policy speech in Washington, the prime minister said the international community must resolve its differences and work together to protect democracy, freedom and the rule of law.
Cooperation was vital if the challenges of global terrorism, climate change, world poverty and international trade were to be met, Mr Blair insisted, adding that the institutions to enable this must be reformed.
He called for the UN secretary general to be given more power over resources, in choosing the secretariat, and to refer long-standing problems to the security council.
The permanent membership of the security council should be expanded to address the anomalies whereby France and not Germany, and China and not Japan, were members, he added.
The International Monetary Fund must also become more representative of emerging economies and the World Bank should sharpen its focus on tackling world poverty, Mr Blair said.
In addition, he said there was a "strong argument" for a multinational system for the safe enrichment of uranium, so not every country had to have their own fuel cycle facilities.
"We have to act not react, do so on the basis of prediction not certainty, and realise such action will often be outside of our own territory," Mr Blair said.
"What that means is that this can't be done easily unless it is done on an agreed basis on principle, on values that are shared as well as fair.
"We must fashion an international community that both embodies and acts in pursuit of global values - liberty, democracy, tolerance, justice. These are the values that can inspire and unify."
He held up Iraq as the symbol of that unification, saying that the critics of military action against Saddam Hussein should support the new democratic government as a model for other states.
"This should be a moment of reconciliation not only in Iraq but in the international community. The war in Iraq split the world - the struggle for democracy there should reunite it," he declared.
Mr Blair made the speech during a trip to see George Bush, and the two men appeared united on Iraq during a press conference last night.
However, today the prime minister issued a warning shot to the US president, saying: "No amount of institutional change will work unless the most powerful make it happen."
Last night, Mr Bush appeared to signal some support for a strengthened UN, although it is unlikely he would accept many of the changes proposed by Mr Blair today.
"I'd like to see a UN that's effective, one that joins us in trying to rid the world of tyranny, one that is willing to advance human rights and dignity," the president told reporters.
He added: "The UN ought to be clear about its desire to liberate people from the clutches of tyranny. That's what the UN ought to be doing, as far as I'm concerned."