The vice president of the Woodley Park branch of American Security Bank said yesterday he resigned last week after his bank discovered he assisted a customer suspected of having illegally obtained more than $2 million in cash from the bank.

Raymond C. Mowchan, the 38-year-old former bank official, denied in an interview that he benefited personally from the transactions and said that he got into trouble by failing to notify his superiors after discovering that the customer had written bad checks and had obtained a loan improperly.

Mowchan said he wanted to give the customer, with whom he said he had no personal relationship, a chance to quietly repay the bank. "I tried to help him," Mowchan said.

But the customer, a businessman whose name has not been divulged by the bank or federal authorities, apparently tried to repay the bank with a series of bad checks drawn on different accounts, according to a source in the U.S. attorney's office.

The source described it as a "check-kiting" scheme, in which the customer wrote a bad check on one account and then covered it with a bad check from another account. "When you're involved in check kiting, in order to cover your bad checks you generate more checks. It just balloons."

Several sources involved in the investigation said yesterday that it is possible Mowchan's actions unwittingly assisted the customer in his scheme, although they cautioned that the investigation is just getting under way and it is too early to tell.

"I don't think the bank official involved gained any money from it," said one of the sources, adding that his mistake "may have been that he remained quiet."

Asked whether he thought he had been duped by the customer he tried to help, Mowchan replied: "To a degree that's right."

American Security, the city's second largest bank, called in the FBI last week after the bank's internal monitoring system detected what the bank later described as "suspicious cash transactions" at its Woodley Park branch, at Connecticut Avenue and Calvert Street NW.

Shortly after the investigation began last week, Mowchan, a long-time employe at the bank, offered his resignation. He said yesterday that he had not been asked to resign by bank officials.

On Wednesday, following a preliminary investigation by the FBI, American Security issued a statement disclosing that one of its bank officers had made "unauthorized and unlawful cash disbursements" to a customer of one of its branch banks in excess of $2 million.

The bank said in its statement that the illegal disbursements were insured by the bank's employe fidelity bond.

Spokesmen for the FBI and American Security declined yesterday to provide additional information on the case.

"The federal authorities asked us not to comment, and we're trying to cooperate with them," said an American Security vice president.

The U.S. attorney's office officially entered the case on Wednesday, according to a government lawyer.