Standard & Poor's Corp. said Wednesday that the slide in Japanese bank ratings is not irreversible, but that strong measures will be needed to regain credit strength because of the tough operating environment.

"The banks remain vulnerable to external factors, such as the declining economy and falling stock prices," the U.S. credit rating agency warned in its "Bank Industry Risk Analysis" report.

"The financial sector's weak fundamentals have failed to improve as shown by the recently announced financial results for fiscal 2000 ended March 2001," S&P said.