A “safe harbor” agreement that protects the underlying assets of securities held by failed banks from being seized by U.S. regulators may be kept in place beyond March, a Federal Deposit Insurance Corp. official said. FDIC officials had wanted to exempt all assets securitized through March 31 to ensure a smooth transition to a new accounting rule that rattled credit markets because of the prospect of more aggressive asset seizures. “I think it’s safe to say that we will need to extend the March 31 safe harbor period,” Michael Krimminger, a special policy adviser to FDIC Chairman Sheila Bair, said yesterday at the American Securitization Forum’s annual conference near Washington.