Widely-differing views on how to tackle the world economic crisis are threatening to sour the atmosphere at the G20 economic summit in London.Two days before the talks, world leaders agree some progress has been made, but admit much more needs to be done. Britain’s Prime Minister Gordon Brown says only co-ordinated action will bring rewards. However France, for one, rejects American and British proposals to spend their way out of recession and President Sarkozy said he will walk out if there is no commitment to tougher financial regulation. The G20 is the start of President Obama’s first major foreign trip, shifting his and America’s focus onto global economics and diplomacy after a heavy emphasis on domestic issues. The leaders know the world is hoping for a clear route out of the crisis. Expectations of success, though, are not high. “In practical terms, not very much can be achieved,” said Fortune Magazine’s Peter Gumbel. “There are so many disagreements. You have the Europeans rejecting the American demand for greater stimulus; you have the Americans and the British rejecting European demands for more financial regulation. However, having said that, there is a very important symbolic element in this meeting, because getting the leaders together, getting them to agree on even something pretty simple, is important.” Security in London has been stepped up in case anti-globalisation demonstrations get out of hand. Many banks will close, fearing they may be attacked for causing the recession. Gordon Brown said he understands people’s anger, but warned it should not boil over this week.