MANILA, JAN. 9 -- As American troops prepare to fight in the Persian Gulf, a hardened Philippine bargaining position and caustic remarks about U.S. commitments in negotiating the future of U.S. military bases here risk causing "irreparable harm" to relations between the two countries, a U.S. special negotiator warned today.

Cautioning the Philippine side against making the talks "an exercise in confrontation," former assistant secretary of defense Richard Armitage criticized a new demand for a five-year "terminal phase-out" of the bases and urged the government to avoid an outcome that would be "interpreted by the U.S. public as an act of anti-Americanism."

Taken as a whole, the statement appeared to represent the strongest public criticism by a U.S. administration of the five-year-old government of President Corazon Aquino. It came at the opening of a crucial session of talks on six U.S. installations, including two large air and naval bases that project American power into the Indian Ocean and Persian Gulf regions.

The most important of the facilities, Subic Bay Naval Base, last week hosted elements of the biggest amphibious assault force assembled by the United States since the Korean War -- part of a U.S. buildup in the Persian Gulf ahead of a Jan. 15 deadline for Iraqi invasion forces to withdraw from Kuwait. The 13-ship task force, including 7,500 Marines, sailed for the gulf Jan. 2 after a few days of shore leave that turned the town of Olongapo into what one Manila newspaper columnist, a Roman Catholic nun, termed "a fiesta in hell." But many local businessmen welcomed the estimated $25 million that servicemen spent on leave during the New Year holiday.

Underscoring the strains in the latest round of bases talks, are intensifying jitters among the Philippine government and populace about the potentially disastrous effect of a gulf war on this highly vulnerable country. With newspapers counting down the days left before war on their front pages, government and military officials have issued public warnings about consequences ranging from oil and food shortages, price increases and civil unrest to casualties among the estimated 400,000 Filipino workers still employed in that region.

Panic buying has stripped supermarket shelves of many basic items. Hoarders have raided shops for rice, sugar and other staples, and prices of some commodities have begun to climb.

Today's remarks by Armitage, later read at a press conference by a U.S. spokesman, came in response to a tough statement Tuesday by the spokesman for the Philippine negotiating panel, Rafael M. Alunan III. Alunan's statement signaled wide differences over fundamental issues in the talks, which Manila insists must be completed by Jan. 31. It said the Philippines is "not interested" in a new pledge by the U.S. administration to use its "best efforts" to obtain compensation for the bases -- in the form of aid -- from Congress, on grounds that such a formula is unreliable.

The Philippines wants any new agreement that would extend U.S. use of the bases beyond the September expiration of a current accord to contain a fixed, multi-year commitment of funds, a provision that U.S. negotiators say is unconstitutional.

Under the current agreement, the United States had promised to make "its best effort" to persuade Congress to appropriate $481 million annually for fiscal years 1990 and 1991. Manila reacted angrily when Congress trimmed last year's figure by $96 million.

The Alunan statement also challenged the United States to make good at the negotiating table its "avowals of friendship" with the Philippines. It added, "The time has come for actions to match rhetoric."

Armitage told the Philippine negotiators: "Such a comment seems inappropriate to us at the time when the United States is on the verge of a major sacrifice in the Persian Gulf in the defense of fundamental principles that affect the entire international community." He said the United States already has started to provide excess military equipment to the Philippine Armed Forces in anticipation of an agreement.

He urged the Philippine side to "consider the message you are sending as it is perceived by President Bush and the U.S. Congress: As Americans prepare to fight and die in the Middle East, Filipinos define their own victory in terms of how many and how quickly U.S. forces can be removed from their country."

The United States has proposed a "phase-down" of U.S. forces here over 10 to 12 years, followed by an arrangement for continued American access to the bases, possibly on a commercial basis. After a number of vacillations in its position, the Philippines is now insisting on the complete removal of all U.S. forces by September 1996 in what it calls a "terminal phase-out."

Armitage said such a formula implicitly rules out any future access relationship and that the United States "simply cannot manage a five-year phase-out" without incurring heavy, unplanned expenses.

In a tacit warning that Washington could opt to abandon the bases, which pump about $1 billion a year into the Philippine economy, Armitage said he was "under no pressure -- particularly from Congress -- to conclude a new agreement."

Reacting sharply to the U.S. statement, Philippine spokesman Alunan said the fact that the Philippine side had agreed to negotiate at all was a "concession to the Americans" and that the country was still "trying to shake off" the legacy of its nearly 50-year colonial domination by the United States during the first half of the century.

"People are also forgetting that we have 400,000 Filipinos in the Middle East," Alunan said, "and many of them are in the front lines, even farther front than some U.S. military units." He said Filipinos indirectly were contributing to the U.S. military operation in the gulf by helping "the Saudi government and the other Middle Eastern countries run their installations. And in case of a shooting war, our people are going to die too."