Nomura Holdings Inc. may face "severe action" by regulators after employees of the country's biggest securities firm leaked insider information, Financial Services Minister Tadahiro Matsushita has announced.

"It's regrettable that information on public offerings was leaked to the sales department of the lead underwriter, which is supposed to strictly manage such information," Matsushita said at a news conference Tuesday. He did not elaborate on the types of action the Financial Services Agency may take, saying it depends on the outcome of the investigation.

Nomura said last week that employees gave nonpublic information used for insider trading in 2010, acknowledging for the first time their role in cases being examined by regulators. The Securities Exchange and Surveillance Commission, the FSA's watchdog arm, has since March recommended penalizing the companies that profited from the leaked information while stopping short of punishing the underwriters who provided it.

The investigation centers on the trading of shares of Japanese companies before they announced equity offerings in 2010. Employees at Nomura, a manager of stock sales by Mizuho Financial Group Inc., Inpex Corp. and Tokyo Electric Power Co., provided information on the stock sales.

"Brokerages in general must hold a high standard of working ethics and comply with the laws and regulations because they handle highly confidential information," said Matsushita, who was appointed as part of a Cabinet reshuffle last week.