Speaking to a business audience, Miliband accused the banking system of having “failed British industry for too long.”

The Conservative-led coalition government set up an Independent Commission on Banking (ICB) last year to explore separating companies’ retail banks from their investment banks, and to probe ways of boosting competition in the concentrated British banking market.

“I urge the government to be bold in implementing the recommendations of the Banking Commission,” Miliband said. The ICB will produce its interim report on Monday, setting up an intense period of lobbying ahead of its final conclusions due in September.

“When everybody up to and including (Bank of England governor) Mervyn King says that banks are exploiting their customers, there clearly is a problem,” Miliband added.

“We need to restore the primary role of banks as intermediaries between savers and productive investment in the economy, rather than as institutions that derive massive profits from speculation.”

Labour has been criticized for favoring a “light touch” regulatory regime for banks during the run-up to the global financial crisis in the final years of the last decade.

The last Labour government, led by Gordon Brown, pumped billions of pounds into bailing out Royal Bank of Scotland and Lloyds Banking Group.

The Labour leader said he was concerned that the banks had not learned from the excesses of recent years.

“We are seeing too much evidence that the banks are simply going back to business as usual before the crisis hit,” he added.

Miliband said banks had lost contact with their clients such as the owners of small and medium-sized businesses in his audience.

“We need to move from call-center banking to relationship banking,” he said.