French President Nicolas Sarkozy said there may not be enough time at the London G20 summit to discuss all the reforms needed to overhaul the financial system and the work needed to prevent other disasters, Reuters reported.

In a commentary to be published in several newspapers, Sarkozy wrote that further meetings may be necessary.

"I am fully aware that we cannot achieve radical change overnight, that there is still a long way to go and that there may well be a need for other meetings, after London, in order to implement the reforms undertaken," he wrote.

Sarkozy wrote he hopes to see "practical results" at the G20 summit on April 2.

"Failure is not an option, the world would not understand it and history would not forgive us for it," he said.

Contrary to reports saying the French president would walk out of the meeting if his demands were not met, Reuters reported officials in Paris said there were no threats in Sarkozy's commentary.

Sarkozy also said stricter rules were needed on tax havens and that France needs to name and shame countries that oppose ending bank secrecy, Reuters reported.

"I want us to (adopt) a resolution which clearly identifies these tax havens and sets out in detail both the changes we expect them to introduce and the consequences which will ensue, should they fail to respond accordingly," he said.

Sarkozy also wrote that the impact of different stimulus packages had yet to be realized and promised to do more if needed, Reuters reported.

"This is the principle I will be defending in London: to do everything necessary for world growth," he said.

Click here to read the full Reuters report.