British Prime Minister Gordon Brown says banks must be reformed so that they are the "servants" of economies and societies rather than the "masters".
In a comment piece to be published in The Observer on Sunday, Mr Brown called for a "reformed and more responsible banking system".
He said banks must act "in the long-term interests of their shareholders" and therefore of the economy as a whole, "not in the short-term interests of bankers."
Mr Brown said the new banking system must become "the servant of our economy and society, never its master."
German Chancellor Angela Merkel has called for rules governing financial markets to be reinforced.