In a coordinated but discreet buildup of force, the United States and it's major naval allies have assembled a formidble fleet of at least 60 warships in the Indian Ocean area to protect the vital Hormuz Strait oil route should traffic be threatened by the Iraqi-Iranian war.

Recent allied moves, harmonized by continuing workng-level discussions among military attaches in Washington, have been carried out without fanfare in deference to concern -- particularly in Britian and France -- that the cumulative effect of such Western naval deployments might generate charges of outside interference in the Persian Gulf conflict.

Press reports on the subject consequently have met with official silence, France, Britian and Australia have recently added naval forces in the areas to strengthen a U.S. fleet in the Indian Ocean and Persian Gluf already amounting to 32 ships since the Iranian crisis, including the aircraft carriers Eisenhower and Midway.

In all, the United States and its allies -- chiefly France -- now filed about 60 ships, twice as many as the 29 Soviet ships monitored in the same region and up by a dozen from the levels of earlier this year. The allied deployments, include three aircraft carriers, half a dozen destroyers and a number of guided-missile-equipped frigates in addition to smaller ships and tenders.

The buildup by the United States took place over the last year in response to the Iranian, then the Afghan crises. France traditionally has maintained an Indian Ocean fleet, but Paris has sharply increased its deployment in the region in recent months, and Britian and Australia have in the last few weeks joined the allied effort with several ships apiece.

Although the U.S. fleet has not grown since the Iranian-Iraqi hostilities, Washington has sent four AWACS reconnaissance planes to the area in response to a request from Saudi Arabia. The planes, flying radar platforms, could be used to supply U.S. and allied ships with long-range surveillance.

French officials in Paris said their participation in the allied buildup demonstrates their own concern over the continuing hostilities between Iran and Iraq and resolve to prevent any attempt at plugging the Hormuz Strait, through which about one-third of the noncommunist world's oil passes -- including half of Western Europe's.

French President Valery Giscard d'Estaing, during a stopover Tuesday in Abu Dhabi on his way to China, said free gulf navigation "is considered by France and the international community to be vital." If it were "put into question or threatened, France could not take a disinterested view of the matter," he added.

This concern also was underlined yesterday by news agency reports that Capt. Bahram Afzali, identified as commander of the Iranian Navy, renewed an Iranian threat to mine the gulf and the strait channel leading out of the gulf into the Indian Ocean if the United States or other Western countries helped Iraq in the war. Although Afzali said there was no need for such action now, he emphasized that Iran has the military capability to carry out the mining.

U.S. Defense Department officials expressed doubt that the Iranian Navy or Air Force actually could close off the 26-mile-wide strait with mines or other ploys such as sinking ships in the channel. At the same time, observers pointed out, there is a range of possible threats to shipping besides mining -- ranging from air attacks to harassment by patrol boats -- that could create a climate of fear in which ship owners would be reluctant to take risks there.

The French officials stressed that their ships were not part of any international task force, an idea floated after President Carter told members of Congress that his administration and U.S. allies were taking measures to protect the strait if necessary. That idea should be ascribed to the U.S. presidential campaign and seen as an effort to portray Carter as a forceful leader in the crisis, they suggested.

At the same time, French, British and other allied officials acknowledged that coordination talks have been going on since shortly after the Iranian-Iraqi conflict erupted during the last week of September. Participating, informants said, are the United States, France, Britian, Australia, New Zealand and, to some extent, riparian nations such as Saudi Arabia, Oman and the United Arab Emirates.

Notably absent were West Germany and Japan, which both depend heavily on Persian Gulf oil and count themselves among U.S. allies. Both countries have constitutional restrictions on use of their military forces outside their home regions.

It was unclear how closely the allied governments are coordinating their ships' movements or the division of missions should an actual threat arise. British officials said only that the fleet has assembled to intervene against any threat to commercial shipping through the strait, which lies between Oman and Iran at the opposite end of the Gulf and some 600 miles from the current Iranian-Iraqi fighting. French officials, like their British, counterparts reluctant to discuss the plans, said the allied navies could sweep any mines laid by Iran, assist tankers hit in any attack or confront any Iranian vessels that tried to harass oil ships.

In addition, they said, the Western ships served as a warning to Iraq about U.S. and European concern over reports that Iraq had planned an attack on three Iranian-held Gulf islands -- Abu Musa and the Greater and Lesser Tumbs -- to be staged from nearby Arab nations such as the United Arab Emirates or Saudi Arabia.

These sources raised the possibilitiy of at least a tacit understanding -- and perhaps more -- that the Gulf Arabs will not allow Iraq to use their soil for an attack on the islands while in return Iran will not attack navigation in the Gulf.

Despite the discretion surrounding the naval deployments, Britian announced yesterday the dispatch of a Royal Navy frigate, the Alacrity, to join the British guided-missle destroyer Conventry and its tanker sent to the increasingly tense region several weeks ago.

Although British officials said more tankers or support ships could prove necessary for the Coventry and Alacrity, other sources described the British deployments as "a token show of force" designed to give an allied flavor to the force composed primarily of U.S. and French ships.

France disclosed earlier this week the reinforcement of its Indian Ocean fleet with a missle-launching frigate, the Suffren, bringing to 20 the number of warships in the French Indian Ocean fleet compared to the usual 14.