Gordon Brown, in his first address to European lawmakers as Prime Minister, has called on Europe to work with America to forge a new "moral" global capitalism.
The UK leader, speaking on Tuesday in Strasbourg, insisted that the financial "hurricane" lashing the world offered an opportunity to promote fairness after years of "irresponsibility".
The G20 summit must push towards better and more transparent regulation, as well as signalling "the beginning of the end for offshore tax havens", Mr Brown said. He also hinted at a bid to get international agreement on rewards for top bankers.
"Let's be honest with each other," he told the MEPs. "Our global economic system has not just developed but been distorted in ways that run contrary to the values we celebrate and uphold in every other part of our lives.
"Values such as being fair to others and taking responsibility for our actions; honouring hard work and not rewarding irresponsible excess.
"Established limits to markets agreed in one country or region are being overtaken by global competition between all countries, and so I say it is not enough to promote self-regulation: we have to agree international standards of transparency, disclosure and - yes - of regulation."
Mr Brown said the world had learned the cost of "unbridled markets", and good societies needed "a strong sense of values".
"I believe that we can, for the first time, agree the big changes necessary for co-ordinated action that will signal the beginning of the end for offshore tax havens and offshore centres," he said.
The Prime Minister insisted the arrival of US President Barack Obama heralded "a new era of heightened co-operation between Europe and America".
"Never in recent years have we had an American leadership so keen at all levels to co-operate with Europe on financial stability, climate change, security and development, and seldom has such co-operation been so obviously of benefit to us and to all the world."
In what aides described as the most pro-European speech he has delivered, Mr Brown lavished praise on the EU, saying it was "uniquely placed" to take the lead in reforms.
He was warmly applauded by the MEPs when he said he was "proud that, by a large majority, our British Parliament ratified the Lisbon Treaty".
Last week's European Council also agreed a further $100billion loan to the International Monetary Fund for emergency bail-outs in the developing world and a £5billion package of spending on renewal energy and broadband.
Mr Brown told MPs on Monday that EU leaders had made proposals to "reshape the global financial and trading system" and do what was necessary to build economic recovery across the world, including rejecting protectionism "that history tells us in the end protects no one".
Mr Brown will return to the UK by next week in time for the G20 summit in London. The G20 was top of the agenda when Mr Brown and Barack Obama enjoyed what the White House called a productive 25-minute phone conversation on Monday.
