Nicolas Sarkozy, the French president, waded into the subprime mortgage crisis that has thrown global markets into turmoil, with a call for G7 governments to work with central banks and the International Monetary Fund to improve financial transparency.

In a letter to Angela Merkel, the German chancellor and acting president of the group of eight industrialised nations, which includes the G7, Mr Sarkozy highlighted his concerns over the weaknesses of the international financial system revealed by the present crisis.