The final round of negotiations aiming to get consensus ahead of tomorrow's G20 summit is under way today.
The summit has been called to discuss ways of dealing with the global downturn and promoting economic recovery.
British Prime Minister Gordon Brown and US President Barack Obama held talks this morning at Downing Street and followed that with a news conference.
At that news conference, Mr Brown insisted Britain and the US were united in their determination to tackle the economic crisis.
'President Obama and I are agreed about the significance of this week's G20 meeting that the world is coming together to act in the face of unprecedented global financial times.'
For his part, Mr Obama stressed that G20 nations should focus on common ground and not 'occasional differences' at the summit.
The US President said differences between world leaders have been 'vastly overstated' ahead of the summit, but he admitted that the leaders will not agree on every point.
Both men will also meet President Hu Jintao of China and the Russian President Dmitry Medvedev during the day.
It will be the first time that Mr Obama and Mr Medvedev have met during their times in office.
French foreign minister Bernard Kouchner said he expected the G20 summit to be ‘rather difficult’.
Mr Kouchner said he expected a confrontation between ‘two worlds: one that wants more regulation, and the other that wants less and which is closer to so-called liberal positions’.
Mr Brown said: ‘What has essentially happened is that the speed and the pace and scope of the global financial changes, the mobility of capital around the world, overwhelmed systems of national regulation.’
The UK prime minister dismissed suggestions that the French president might walk out of the summit if he did not get the tough global financial regulation he wanted.
Mr Brown added: ‘We are within a few hours, I think, of agreeing a global plan for economic recovery and reform. I think the significance of this is that we are looking at every aspect...
‘Of course it is difficult and of course it is complex - we have a large number of countries - but I am very confident that people not only want to work together but we can agree a common global plan for recovery and reform.’
US President Barack Obama insisted he remained ‘a big believer in global markets’ and wished to see them functioning well.
But he added: ‘What we have to understand is that that is going to require some sort of regulatory framework to ensure it doesn't jump the rails. That is something that I think we are going to be able to put together.’
Mr Obama rejected suggestions that the leaders meeting in London were deeply riven by splits over fiscal stimulus, regulation of the financial system and support for poorer countries.
‘I am absolutely confident that this meeting will reflect enormous consensus about the need to work in concert to deal with these problems,’ he said.
There was ‘complete concurrence’ among G20 leaders about the need to protect emerging markets and help poorer countries through the recession, said Mr Obama.
Speaking earlier, Mr Sarkozy warned that France would not tolerate ‘false compromises’.
‘As of today, there is no firm agreement in place,’ he told Europe 1 radio. ‘The conversation is going forward, there are projects on the table. As things stand at the moment, these projects do not suit France or Germany.’
But the plans being discussed by G20 leaders at the London Summit represent ‘a missed opportunity’ in terms of setting the world on a low-carbon path for the future, a report warned today.
Some of the public spending programmes put forward actually run the risk of locking the world into a future of continued greenhouse gas emissions, the study commissioned by environmental charity WWF and the low-carbon group E3G found.
