The U.S. attorney's office here is investigating whether other New York City banks besides the Chemical Bank have been used for money laundering operations or have failed to make reports under the government's Bank Secrecy Act.

"The investigation is continuing into the types of conduct that are the subject matter of the indictments brought" against Chemical Bank, said Robert B. Fiske Jr., U.S. Attorney for the Southern District of New York.

Fiske would not elaborate. Sources, however, indicated that the Chemical Bank case had triggered an investigatation of other banks but that no indictments were imminent.

Chemical, the fifth largest bank in New York City and the sixth largest in the country, was indicted Thursday for failing to report more than 500 transactions totaling $8.5 million that were covered by the federal Bank Secrecy Act. Some of these transactions, it was charged, were money laundering operations for narcotics dealers.

Also indicted were three former Chemical employees, including a bank vice president who was charged with lying to a grand jury about his knowledge of the transactions, and a branch manager and assistant branch manager for failing to report as income money they allegedly received for washing $1.6 million in funds for the narcotics dealers by converting small bills into ones of large denominations.

The Bank Secrecy Act requires banks to report all cash transactions involving more than $10,000 to the Internal Revenue Service. It was passed to detect use of banks by criminals or tax evaders.