The Treasury Department yesterday dismissed as "completely groundless" reports that Taiwan has pulled $35 billion out of U.S. banks because of fear that a Persian Gulf war would heighten recession and weaken the banks.

U.S. bankers and a Federal Reserve official also discounted the $35 billion figure, although some analysts suggested that Taiwan does harbor concerns about the U.S. banking system.

If such a huge sum were siphoned from the banking system, it would have had a quick and visible impact on financial markets, analysts said. Moreover, Federal Reserve figures show that banks in New York, where the financial industry is headquartered, have remained roughly stable in size in recent months.

Over the longer term, however, Taiwan's central bank has been cutting back its holdings in U.S. banks. They totaled about $26 billion at year-end 1988, $20 billion at year-end 1989 and $12.5 billion last September, according to Treasury figures.

Asked about the Taiwanese media reports during a lunch with area business executives at The Washington Post yesterday, Federal Reserve Chairman Alan Greenspan said, "That's not my impression of what the actual data are."

One American banker was more direct: "Anybody talking about {Taiwan} pulling $35 billion out of the U.S. banking system is out to lunch."

Nonetheless, Taiwan does seem to be a bit jittery about the stability of U.S. banks, where it keeps some of the $70 billion dollars in reserves that it has built up through trade surpluses.

According to one consultant familiar with Taiwan, major U.S. banks that do business with Taiwan have recently sought, through special meetings and communications, to assure authorities there that the banks are solid.

The current recession and weakness in real estate prices has battered many U.S. banks. Large-scale withdrawals by foreign depositors would be a new and unwelcome pressure on their profits and long-term stability. Thus, the report from Taiwan drew wide attention.

Foreign countries typically keep reserves of "hard" currencies that can be used in world trade, such as the U.S. dollar, Japanese yen and German mark, as a sort of national savings account for a rainy day. Typically, they are scattered about the world in various commercial banks, while some may be kept on deposit with other central banks.

Reports from Taiwan said that the withdrawals were based on fear that war in the Persian Gulf would worsen U.S. economic problems.

In a telephone interview yesterday, Taiwan central bank governor Samuel Shieh said that U.S. money movements by his bank were "routine" but declined to say how large they were, calling that a "banking secret." He termed the Taiwanese press reports "speculative" but would not confirm or deny them.