Business  |  David Cameron  |  G20

"The progress made by the G20 has been impressive but it has now reached a critical juncture," Stephen Green, chairman of HSBC and the British Bankers' Association (BBA), said in the letter to Prime Minister David Cameron.

"We encourage you to press your fellow leaders to commit to the coordinated implementation of measures, to maintain the openness of their markets and avoid decisions which could result in a retreat to protectionism and regulatory arbitrage."

G20 leaders are due to meet in Canada this weekend to discuss regulation reforms.

Banks in Germany, France and elsewhere in Europe have also sent letters to leaders ahead of the meeting, industry sources said.

The G20 needs to avoid introducing regulation that results in reduced choice, competition and availability of credit and would damage the economic recovery, the BBA said.

Green's letter, sent on Wednesday, said proposals to change the net stable funding ratio, credit valuation adjustment model and counter-cyclical capital buffers all needed "further consideration and calibration."

Banks have said proposals for them to hold more capital and liquidity and a wider regulatory crackdown could derail an economic recovery and needs to be introduced globally and with careful timing. They reckon it could cut 3 percent off economic growth over the next five years in the United States, euro zone and Japan and cost almost 10 million jobs.

(Editing by Simon Jessop)