Paris  - French President Nicolas Sarkozy has threatened to walk out of this week's summit of G20 nations in London if it does not look to be achieving concrete results, the daily Le Figaro reported on Tuesday.

"If there is no progress in London, there will be an empty chair. I will get up and leave," Sarkozy said in an aside during a recent meeting of his cabinet.

The newly appointed deputy head of Sarkozy's office, Xavier Musca, on Monday underlined France's insistence that irreversible decisions be taken at the summit.

"The worst summit result, even worse than failure to agree, would be a false success, a soft statement that sounds good but does not lead to any commitments," Musca told journalists in Paris.

The French are demanding that a list of uncooperative tax havens be drawn up and that a system of sanctions be agreed for financial institutions that do not cooperate in the fight against income tax fraud and money laundering.

Paris also would like to see a system put in place that prevents equities traders from taking unreasonable risks.

A French government source said that a framework involving a system of measuring risk and earnings should be put in place as well as a supervisory organization to demand that banks intervene to either reduce risk or increase capital to cover potential losses.

Both of these issues are certain to be controversial in London.

On Monday, the host of the G20 summit, British Prime Minister Gordon Brown, warned that tough negotiations lay ahead.

"These are difficult and complex problems. It will not be easy to reach the conclusions that I believe are necessary for the world economy," Brown said. (dpa)