Leadership of the high-priced world of art and antiques is up for auction and New York, not London or the Continent, may well be the highest bidder.

At last week's third annual World Antiques and Fine Arts Market Conference here, about 300 antique dealers, colectors and experts - and, ominously, one Internal Revenue agent - heard other experts speculate that New York, drawing on America's young money, might win the prize from the Old World.

The United States' relatively stable currency, power and prosperity are listed as reasons for the flow of luxury goods in this direction, as exotic collections once flowed into Great Britain during its empire years. Yet the American interest seems to be only a part of a worldwide antiquity mania.

There has been what Peter Wilson, chairman of Sotheby Parke Bernet Worldwide, calls "a dramatic increase" in the value of what he tries not to call "junk."

London is still not yet a second-rate power in art/antique sales. Wilson says he expects the biggest sale of this century to be the one coming up May 18-27 in England: the contents of the Earl of Rosebery's "Mentmore House." The collection dates from Meyer Rothschild, one of the founders of the family fortune, whose daughter Hannah married the Earl of Rosebery, a prime minister under Victoria. The family holdings include "several Rembrandts," 40 18th-century French commodes, a 16th-century Italian Doges cap, hundreds of pieces of vermeil found in drawers all over the house, and a secretaire which belonged to Marie Antoinette, and was found in the coal cellar. Also up for sale is the 60-room mansion and its 400 acres in Buckinghamshire. A charter flight will take American buyers over for the sale. "The sale should total $5 million or more," Wilson says.

Wilson calls the current feeling about antiquities "the new religion."

"You can see this interest in art also reflected in the increase in museumgoers, books and television programs about art and antiquities. When the world might vanish tomorrow, we all of us look for something to hold onto," he says.

"Interestingly enough, during hard times and rumors of wars in Europe, Europeans invest in art, especially that portable enough to be secreted upon the person. But Americans buy most in times of peace and prosperity.

"I think that New York, if it hasn't already, will become the center for traffic in fine art. It is strange, but the desire to collect seemed to evaporate in England before World War I, before the British were economically or psychologically outbid. The decline of the British collector started before we had any worries about money."

They're now saying, Wilson adds, that "the sun never sets on Sotheby's."

For the first time Sotheby's of New York, in its 1975-76 auction year, equaled Christie's and Sotheby's in London with sales of $71 million each. Adding in Sotheby's Los Angeles office, its American sales came to $80 million. When Sotheby's bought Parke Bernet 12 years ago, the New York auction house stood third behind Sotheby's and Christie's.

Gray Boone, editor/publisher of Antique Monthly, organizer of the Antiques Market Conference, estimates the annual turnover of antiques in the United States at $3 billion.

Christie's of London, meanwhile, is coming to New York, too. It will be here this spring, as Christie, Munson and Woods International Inc., bringing $20 million in capital investment. One thousand bidders could be accommodated at once in the firm's new salesroom, the renovated (for $1.2 million) Delmonico Hotel ballroom in what is now a posh apartment house at Park Avenue and 59th Street.

There are other manifestations of the growth of the antique business in New York.

The East Side House Settlement's 23d annual Winter Antiques Show expects to close today after eight days of record attendance and sales. And dealers such as the Kennedy Galleries in posh shops and in groups such as the Manhattan Art & Antiques Center at 1050 Second Avenue at 56th Street are prosperous beyond measure. The 336d annual Madison Square Garden antiques show Feb. 19-27 is expected to roll money down the aisles with exhibits including the vastly popular "collectibles" category.

(In Washington, despite its ice and snow storms, the recent annual Thrift Shop Charities Washington Antique Show had a record attendance on Saturday, and a total for the show of 10,000 visitors. A new group of investors has just put money into C. G. Sloan auction house, the old favorite of Washington socialities, to make it once again competitive with Weschler's auctioneers. And it seems that everywhere you turn, yesterday's junk dealers are becoming antiquarians over night.)

"The time is right," says Guy Hannen, president of the New York Christie's. "As a matter of fact, I expect we would have been here two or three years earlier if we could have found suitable quarters." Christie's has had a New York office for some time, to solicit objects for sale and buyers, but no auction rooms.

"I don't expect that we will be so much cutting into Sotheby's business as we will be generating new business of our own. And though we recognize that New York might possibly overtake London in a few years, so far, even though we have opened other new offices in Geneva and Amsterdam, none have diminished London's business."

Sotheby's people seemed to agree there is plenty of business to go around. But the companies agree on little else.Christie's plans to institute a "buyer's premium," a 10 per cent surcharge on every thing purchased (in addition to 10 per cent commission charged the seller). Sotheby's, on the other hand, charges sellers on a sliding scale that can amount to 25 per cent of the first $1,000, up to 12 1/2 per cent of sales prices over $15,000. Both charges cover the auction houses' profits, plus the cost of catalogs and such. Sales tax is extra. John L. Marion, Sotheby's New York president, has said he expects the Christie's charge to be about as popular as "the stamp tax."

John Floyd, chairman of Christie's International, says that prices in London were not depressed following the addition of the buyer's premium in London two years ago.

All of the experts spoke of variations in the tastes of different countries. Floyd expects New York to be an especially strong market in art nouveau, Americana and contemporary art. Geneva, he says, is especially interested in jewelry.

Adds Wilson: "Our horizons are constantly widening in what we consider art: Think of the big Egyptian.African and Mexican art museum shows.

"There also has been a rise, a dramatic increase, in the value of the unvaluable object - I'm trying to avoid the word junk. More and more people are realizing that for a few hundred dollars they can put together interestings, medieval pottery, or artifacts of unknown use. They enjoy showing their objects to people and so we realize nothing antique is beyond our contempt.

"There has been a curious increase in Victoriana. Some of the pieces do have a marvelous devil-may-care look, but there are some slavish 19th-century imitations of 17th-and 18th-century pieces which are bringing prices which to an alarming extent are close to the orginals."

John Bly, a London dealer and appraiser, says prices for antiques in Great Britain are currently as high as in New York. "And for the last 12 months there has been a shortage of goods, even though the prices are exhorbitant. The goods are to be found, but you have to get off the beaten track, look in the smal junk shops, for instance."

Bly adds, though, that the European buyers frequently were looking for different things than the Americans. "The Dutch, for instance, have been coming over with lorries and loading up, especially with furniture and Delft imported originally from their country, as well as 17th-and 18th-century goods showing the Dutch influence. The French are interested in Victoriana of the 1850-1860 exhibitions. The Germans are the most discriminating, choosing late-18th-century pieces. The Arabs like the flamboynat 19th-century pieces."

Contrary to most opinion, there is no worldwide shortage of good antiques, Bly says. "There was a tremendous amount of furniture made and imported into England in the late 17th to 19th century. For instance, one joiners company imported 6,582 tea table tops. George Seddon had 400 workmen. Another shop imported 17,000 clockworks."

A recent survey by Clark, Nelson Ltd. for Sotheby's Parke Bernet showed that New York's buyers are often from other parts of the country. On the other hand, their survey said that despite rumors New York has had no great influx of foreign buyers since the Japanese in 1972-73, though the Iranians are currently said to be buying some amoung of ancient Persian goods.

At the antiques conference, Clement Conger, White House curator, presented the Antique Monthly award for service in antiques to Carlisle Humelsine, president of Colonial Williamsburg. Conger was the 1976 winner. Other speakers included two Washington experts, Huntington T. Block, an insurance executive specializing in th art/antique field, and William Lehrfeld, a lawyer. The two-day sessions were held at the Pierre Hotel on Fifth Avenue.