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British Prime Minister Gordon Brown called Tuesday for this week's G20 summit to restore a sense of morality to the bruised world financial system, as leaders began arriving for the crunch talks.
Thursday's one-day meeting on the global financial slowdown will discuss giving more cash to the International Monetary Fund (IMF) to help struggling states, tightening financial sector regulation and boosting world trade.
But calls by the US -- whose President Barack Obama was due to touch down later Tuesday -- for a coordinated fiscal stimulus are likely to cause tensions with European nations like France and Germany which are strongly opposed.
French President Nicolas Sarkozy has warned he will not accept any consensus ignoring his calls for tighter financial market regulation and has reportedly said he will "get up and leave" the G20 if there is no progress on the issue.
Brown was embarking on a flurry of public speeches and private diplomacy in the final 48 hours before the summit as he bids to shore up areas of agreement.
He is "working the phones very hard at the moment", his spokesman said Tuesday, adding: "We have made a huge amount of progress in recent weeks towards agreeing a consensus but clearly there's more to do."
Brown emphasised the need for regulation to have a moral dimension during a speech at London's historic Saint Paul's Cathedral.
"I believe that the unsupervised globalisation of our financial markets did not only cross national boundaries -- it crossed moral boundaries," he said, in an address peppered with religious references and watched by Australian premier Kevin Rudd and Bishop of London Richard Chartres.
"Most people want a market that is free, but not values-free, a society that is fair but not laissez-faire.
"And so across the world, our task is to agree global economic rules that reflect our enduring values."
Although the summit itself is Thursday, business gets under way Wednesday with bilaterals between leaders including keenly-watched first meetings between Obama and Chinese President Hu Jintao, plus Russian President Dmitry Medvedev.
Wednesday is also likely to be marked by major protests about the state of the world financial system in London, and Brown has warned that "no violence can be tolerated."
"No intimidation of people is allowed and the police will act very quickly if there is any threat to property or people," he told ITV television Tuesday.
More than 2,500 officers will be on duty to counter the threat of violence at the G20 in an operation costing more than 10 million pounds (14.4 million dollars, 10.6 million euros).
Another issue likely to be on the agenda at the summit is boosting world trade, which has been badly hit by the slowdown.
The World Trade Organisation (WTO) said this month that exports would fall around nine percent in 2009, the biggest contraction since World War Two.
World Bank chief Robert Zoellick urged G20 leaders to back a new 50-billion-dollar (38-billion-euro) trade liquidity fund and warned again that 2009 would be a "dangerous year."
"This is not a moment for complacency. It is not a day for expressing false confidence that all has been done that can be done. It is not a time for narrow nationalist or even regional responses," he added.
