Bank regulators warned banks to be on guard against increasingly clever computer hacking on Tuesday, indicating heightened alert against security breaches that have plagued government and corporate institutions in recent weeks.

The Federal Financial Institutions Council -- an interagency group that includes the Federal Reserve, the Office of the Comptroller of the Currency, and the Federal Deposit Insurance Corp -- issued a reminder to banks to use more than one form of authentication for online consumers.

Fraudsters have continued to develop and deploy more sophisticated, effective, and malicious methods to compromise authentication mechanisms and gain unauthorized access to customers' online accounts, the council said.

Regulators are concerned protections put in place in response to recommendations six years ago have become less effective, they said.

Programs that record a computer user's keystrokes have been increasingly effective in stealing identifying information and passwords, regulators said.

Institutions should no longer rely on one form of customer authentication, they said.

(Reporting by Mark Felsenthal; Editing by Padraic Cassidy)