The Bank of New York's top executive today defended his company against allegations that it failed to curb a massive money-laundering operation, saying that he and other employees do not tolerate questionable activity.

"Our reputation, built on our collective hard work and sound business practices, is our most valuable asset," Thomas A. Renyi, the bank's chairman and chief executive, said in a note to employees. "We will do whatever is needed to prevent illegal or improper activities that involve the Bank. Period."

It is the first effort by Renyi to boost the morale of 17,000 company workers around the world after disclosures that investigators in the United States and abroad are probing whether several accounts at the bank were used by organized crime and others in Russia to launder huge sums of money.

Investigators believe that a company called Benex Worldwide Ltd. may have moved $10 billion or more through the accounts. A week ago, officials seized $20 million from two accounts and subpoenaed thousands of pages of documents from the bank. Some officials familiar with the case question why bank officials didn't identify the apparent problem sooner.

The bank has acknowledged the investigation, saying the firm was cooperating with authorities and noting that no one has accused the bank of any wrongdoing. It suspended two executives after news of the investigation surfaced.

Bank officials last week fired one of those executives, London-based Lucy Edwards, saying an internal inquiry turned up evidence that she had falsified bank records and violated internal policies.

In Renyi's two-page letter, which was obtained from an employee, the chief executive said he had previously been unable to discuss the case publicly because of the "confidentiality of the investigation." He said that because the case has become public, "I want you to hear my views directly."

Renyi suggested that the case might be more far-reaching than previously thought, saying "this investigation involves many financial institutions in many countries."

"We cannot say at this point how long it will take to complete the investigation," he said.

Company officials declined to elaborate.

While Renyi stressed the procedures the bank follows to root out illegal and inappropriate activity, he also pledged to follow up on any shortcomings that might emerge from the investigation.

"If any investigation into this matter indicates flaws in the Bank's internal procedures, they will be addressed immediately. If any investigation indicates inappropriate action by any Bank employees, we will take prompt action," the letter said.

CAPTION: The Bank of New York says it is cooperating with an investigation into possible money laundering involving Russian organized crime.