Bank of New York Co. yesterday launched a $1.5 billion bid for rival Irving Bank Corp. which, if it succeeds, would be the biggest hostile takeover in U.S. banking history.

"It's a pretty bold move," said James J. McDermott, a banking industry analyst at Keefe Bruyette & Woods, a brokerage firm. "It's a groundbreaker from the standpoint of the hostile nature of the transaction. You don't do that in the banking industry, so this is very blunt."

J. Carter Bacot, chairman of the Bank of New York, said his company decided to make the highly unusual hostile offer after Irving officials rejected overtures for a friendly merger. "We talked to them and didn't seem to make any headway," he said in a telephone interview. "We thought we'd just put the offer out, because it looked like an attractive proposal all the way around for them and for us."

Officials of Irving, whose principal subsidiary is Irving Trust Co., a major New York bank, said in a statement that they would study the bid and respond "in due course." But in a letter to employes, the company said it believed its long-term interests "are better served by Irving Bank remaining independent."

"That the Bank of New York would proceed as a hostile raider surprises us, and suggests that the Bank of New York is perhaps interested in protecting themselves from takeover, rather than seeking to create a stronger banking institution," the letter said.

The takeover bid comes at a time of heightened concern in Congress and among regulators and industry executives about both consolidation in the banking industry and hostile corporate takeovers in general. Congress is considering how far to deregulate banking to allow the industry to be more competitive, and at the same time is working on legislation to curb many perceived abuses of companies and shareholders in hostile takeovers.

The combination of the two banks would create the 11th-largest bank holding company in the nation, with about $42 billion in assets, increase Bank of New York's position as the leading retail bank in the New York suburbs and generally increase the bank's presence in national banking and securities processing markets. "In toto, we'll have a stronger position in all the major growth areas," Bacot said. "It gives us good size. ... We've been competitive to date, but this would make us even more so."

If successful, Bank of New York's bid would be the largest hostile bank takeover ever. First Interstate Bancorp made an abortive hostile takeover offer for BankAmerica Corp. last year, and there have been a handful of small hostile bank takeovers.

Until now, the most successful hostile bank takeover was the purchase of what are now Washington's First American Banks by a group of Middle Eastern investors then lead by Bert Lance, President Carter's first budget director.

The merger would require the approval of the Federal Reserve Board and New York banking authorities. Many banking industry officials and analysts believe that hostile bank takeovers are scrutinized more closely by regulatory agencies, but J. Carter Bacot, chairman of Bank of New York, said in a telephone interview that he believed regulators "are more concerned with {financial} ratios and things like that than they are in the circumstances of the deal."

Under the terms of the offer, Bank of New York would pay $80 in cash each for 8.6 million -- 47.4 percent -- of Irving's 18.1 million shares, and exchange 1.9 shares of Bank of New York common stock for each of the remaining shares. Bank of New York said it already owns about 900,000 of Irving's shares, or 4.9 percent.

With Bank of New York stock closing yesterday at $43.37 1/2, up $1.50, the offer has a value of about $81 a share.

Irving stock soared on the New York Stock Exchange yesterday, jumping $25.75 to close at $78 in active trading.

Some analysts suggested that Bank of New York would be forced to raise the price slightly to convince Irving to agree to the deal and thus avoid any regulatory headaches.