WASHINGTON — A big new decline in bank earnings makes it increasingly clear the government fund insuring deposits will sink to a historic low and need more money, a top regulator said Tuesday.

Hurt by sinking real estate values in the Northeast, commercial banks earned $3.75 billion in the July-September quarter, down 29 percent from the previous quarter, the Federal Deposit Insurance Corp. said.

Profits slipped from $5.4 billion in the second quarter and $6.3 billion in the first three months of the year.

FDIC Chairman L. William Seidman predicted continued bleak news when results are reported for the final three months of the year, adding to pressure on the deposit insurance fund.

He estimated the insurance fund would lose $4 billion this year. That would leave only $9 billion standing behind $2 trillion in deposits.

Seidman began the year saying the fund likely would break even and as recently as September estimated the loss at $3 billion.

On Tuesday, he said “it’s increasingly clear that the fund ought to have a recapitalization plan so that it is in place if it is needed.’

“It will not mean taxpayer money. It will mean the banks will have to pay more,” he said.

Banks are already seeing their deposit insurance premiums increase by more than 60 percent from 12 cents per $100 of deposits in 1990 to 19.5 cents next year.

The Treasury Department is considering a variety of plans for tapping banks to further shore up the fund.

Eighty-nine percent of the nation’s 12,399 commercial banks made money in the third quarter. The profitability of small banks, with less than $100 million in assets, suffered only slightly, but problems in larger institutions in the East dragged down the industry totals.

Maine was one of the eight states and the District of Columbia where banks lost money. The others were Arizona, Connecticut, Maryland, Massachusetts, New Hampshire, New Jersey and New York.

Maine’s third-quarter losses of $21 million compared to a third-quarter profit last year of $26 million.

Delinquent real estate loans, in which borrowers are behind on their payments by three months or more, rose 12.9 percent to $31.3 billion in the third quarter.

Banks, nevertheless, continued to increase real estate lending, which accounted for three-quarters of their asset growth.

The real estate delinquency rate was highest in Rhode Island, 14.66 percent, followed by Arizona, Massachusetts, Connecticut, Texas, Oklahoma, New Hampshire, Louisiana, New York, the District of Columbia, New Jersey, New Mexico and Colorado.

However, the rate was headed down in the Southwestern states and up in the Eastern states.

“The pattern quite clearly is the East Coast, particularly New England, shows increasing weakness,” Seidman said.

Reported real estate problems on the West Coast have not shown up yet in banks’ balance sheets, but probably will when fourth-quarter results are reported, he said.

“All in all, the outlook for the fourth quarter has to be bleak,” he said.

Consumer loan delinquencies are also rising. They were up 10.4 percent to $14 billion in the third quarter.

The FDIC said that banks paid out 80 percent of their reduced earnings as dividends to stockholders, which Seidman said was too much.

For the first time, the FDIC issued a report on the 479 savings banks it supervises. These state-regulated institutions — a hybrid of a commercial bank and a savings institution — are located primarily in the Northeast and concentrate on real estate lending even more than commercial banks.

They lost $771 million during the third quarter. During the first nine months of the year, 35 percent of the savings banks lost money and as a whole lost $1.2 billion, compared with $20 million in earnings during the same period of 1989.

However, they remain well capitalized. On average, their owners’ investment represented 7.02 percent of the savings banks’ assets. Capital acts as a cushion between losses and the insurance fund.