DAVOS, Switzerland (Reuters) - Business leaders said they were aghast by the culture of banking and its excesses following revelations that a trader at French bank Societe Generale had lost $7 billion (3.5 billion pounds) through possible fraud.

"It's something that further damages the image of banking at a time when people are already very concerned about risks," Intesa Sanpaolo (ISP.MI: Quote, Profile, Research) Chief Executive Corrado Passera told Reuters on the sidelines of the World Economic Forum.

SocGen (SOGN.PA: Quote, Profile, Research) revealed on Thursday a junior employee on its derivatives trading desk earning less than 100,000 euros (74,000 pounds) a year had confessed to carrying out a sophisticated fraud, triggering 4.9 billion euros in losses as his trades were cancelled in volatile markets.

"I've got 200,000 employees working every day, many of them in factories, doing an honest job. What I do is about bricks and mortar," said a senior executive at one of the world's largest companies, who spoke on the condition of anonymity.

"But when I look at these bankers, I have to say that I'm a bit ashamed for them. There needs to be a little bit more common sense."

Mexican central bank governor Guillermo Ortiz said regulators should not rush to impose new, heavy-handed rules but added the scandal headlines and the U.S. subprime mortgage crisis risked damaging trust in the financial system.

"The worst thing is the damage to confidence," he told Reuters.

Another major central banker was overheard exclaiming in the crowded WEF-meeting corridors: "They said it was a lone trader! That's impossible! Haven't they ever heard of risk-control systems?"

Veteran bankers embarked on soul searching after the news, which forced some of Europe's most powerful financiers and members of the French establishment to bow before the world in shame.

"Is there something wrong with banking? I think so," said one head of investment banking at a major European group. "There is no longer a culture of banking. There's a culture of prima donnas. They all just want the power, they want it bigger and faster."

"It's all about these big giants who've gotten ahead of themselves," the banker said.

REALITY CHECK

Outside the financial sector, business leaders did not withhold scorn for the high-flying bankers who are now being blamed for putting the brakes on a five-year global growth streak due to excesses in lending and lax controls.

"Greedy bastards?" mused one head of an international holding company, who declined to be named. "The guys in the real economy are out there managing factories and supply lines and product delivery. They're just chasing higher yields."

Economist Fred Bergsten, director of the Peterson Institute for International Economics, said the SocGen scandal raised doubts about the solidity of the financial system and compounded other threats to economic growth.

"One thought that they had their risk systems under control. This obviously raises fundamental questions about that," he said. "One has to look across the board to see if others aren't vulnerable to the same disease."

Heinrich Hiesinger, head of Siemens (SIEGn.DE: Quote, Profile, Research) industrial unit, said the banking-sector fiascos of late risked damaging confidence in the overall economy.

"We would have thought that their risk systems were more under control," he said. "If the trust has gone away from the market then our clients could stay away."