Winfield M. Kelly Jr., the millionaire county executive of Prince George's County, ownes $375,000 to Suburban Trust Bank, according to a financial disclosure amendment filed this week in Upper Marlboro.

Kelly, whose personal finances have been handled by a blind trust since he entered public office in 1970, had until this week never reported the bank loans of his yearly disclsoure statements. A couty law, in effect for several years, requires public officials to list "liabilities owned to persons doing business with the state, county or any state agency."

Suburban Trust Bank, the largest financial institution in Prince George's, handles the payroll and tax collection accounts for the county government at an annual fee of $40,000. Suburban Trust also holds more of the county's short-term interest-bearing deposits than any other bank.

Kelly failed to report eh substantial bank debts in his previous disclosure statements because his advisers did not believe the bank was actually doing business with the county, according to accountant Joseph W. Poole, one of three trustees for Kelly's blind trust.

"It was my interpretation that the banks had a trust or fiduciary relationship with the county, not a business relationship," said Poole, himself a director of the prince George's State Bank. "But now I understand that the banks bargain with the county for the services they perform and, as such, it is a business relationship.

Poole said that he filled out the financial disclosure forms for Kelly, who in theory is supposed to have no knowledge of what holds in the blind trust. After The Washington Post learned of the bank debts and asked Poole why they were not listed, however, the accountant discussed the matter with Kelly, who instructed him to file the amended statement.

"This whole business of financial disclosure kind of shoots holes in blind trusts," said Poole. "Ideally, Mr. Kelly should have no idea what his debts and assets are or where they are."

"I never really questioned what was on the disclosure forms," Kelly said yesterday. "I just signed them."

Kelly said that after he instructed his accountant to list the bank loans he wrote a letter to the Prince George's Board of Ethics asking it to rule on whether such loans had to be revealed. The ethics board, which was only recently empowered to rule on the veracity of county disclosure statements, has not yet responded to Kelly's request.

According to Poole, Kelly's line of credit at Suburnabn Trust Bank goes back to the 1950s, when Kelly and his father, Winfield M. Kelly Sr., opened a lunchwagon business in the county, selling half-smokes (large sausages) and soup at factories and construction sites.

By the time Kelly sold the lunchwagon business in the late 1960s to ARA Service Inc, a Philadelphia-based food and vending company, he had expanded his once-merger personal fortune into a broad-based stock and real estate empire worth about $1.5 million.

"All of the borrowings [from Suburban Trust Bank] were to further his business career and all were fully collateralized by stockholdings and real estate," said Poole. "There have been times when his debts were virtually nothing and times when they approached $1 million. The notes have always been paid on schedule, although some are dependent on the sale of stocks."

Poole said the most of the money was borrowed before Kelly was elected to the County Council in 1970. However, in 1972 and 1974 Kelly's trust took out bank loans for a condominium and real estate venture to Myrtle Beach, S.C. According to Poole, the Kelly trust "took a bath" on that venture.

Kelly's financial disclosure statement shows that his trust owns stock in five corporations - ARA Services, Macke Co. of Cheverly, Allied Chemical Corp., American Can Co., and Potomac Electric Power Company. The total worth of those stocks is approximately $400,000.

In addition, Kelly's two busines partnerships - Kelly Enterprises and Winkel Limited, both primarily real estate-oriented - are said to be worth about $800,000.

Suburban Trust Bank officials would not comment on their loan transaction with Kelly. Poole said that Kelly was not given preferential rates by the bank. Kelly said there was no relationship between his personal loans and the county's business dealings with the bank. "There was nothing like a quid pro quo," he said. "That's preposterous."