The style-conscious shopper in Saudi Arabia or Hong Kong can find Pierre Cardin clothes, ties and shoes in the better shops. The only trouble is the products are fakes made and sold by someone illegally using the Cardin label.

The French fashion designer joined Special Trade Representative Robert Strauss yesterday to publicize the need for curbing international commercial counterfeiting which is costing manufacturers tens of millions of dollars, perhaps even $100 million, annually. The couturier is the spokesman for a coalition of 19 American and European businesses urging trade negotiators in Geneva to get governments to seize and destroy fake merchandise at ports of entry. GATT negotiations resume next Tuesday.

Pierre Cardin, S.A., produces more than 150 products, ranging from electric razors to fruit juices, in three hundred factories worldwide an sells them in 40 countries including China and the Soviet Union. Sales are $250 million annually. Yet the designer complained yesterday he cannot do business under his own name in Indonedia because someone else already has registered his trademark and is selling Cardin fakes imported from Hong Kong.

Strauss admitted counterfeiting would probably never be stopped completely but added that a significant first step would be increasing the economic penalty for counterfeiters by having customs officials confiscate offending goods. Under current law the manufacturer can usually reexport his goods after removing the phoney label and sell them in another country after attaching a new bogus label.

Commercial counterfeiting has become more prevalent in recent years as the popularity of international brand names has spread. The most notorious copiers operate in Taiwan, Hong Kong, Singapore, South Korea and Italy, According to William N. Walker, formerly deputy special trade representative. Merchandise is sold primarily in the Middle East, Eastern Europe, North Africa, and to a limited extent, in Latin America. Now counterfeit watches, perfumes, and cosmetics and beginning to penetrate U.S. markets.

Besides large-losses to maufacturers, Walker emphasized the consumer may also lose. Because the merchandise is usually passed off as the real thing, it is sold at high prices, although its quality is often inferior. This leaves the buyer - as well as the unknowing merchant who sold the fakes - without recourse if something goes wrong. Cartier has a "Sorry" letter it returns to people who send back fake watches for repair.

The coalition of international manufacturers was formed in April of this year by Levi Strauss & Co. which claims the worldwide craze for its jeans now costs the company several million dollars a year in counterfeits. At the press conference Strauss displayed two pairs of Levis, one made in Taiwan and seized in Paraguay, and the other made in Israel. Manufacturers had succeeded in faithfully reproducing the garments, labels and instructions from Plates stolen from the company.

Walt Disney Productions puts its losses from pirated films at $10 million annually. The makers of Johnny Walker and Beefeaters discovered bottlers imitating their alcohols in Germany and Holland. Bogus Gillette Blue Blades were seized in Israel before they could be exported. And Pfizer found an Italian doctor making its hog fattener Mecadox in a barn outside Florence.

Levi Strauss has employed former FBI agents to track down fakes. A former member of Scotland Yard's fraud squad now specialized in hunting commercial counterfeiters in England. Though the companies realize the burden of spotting illegal merchandise will always be up to them, they are now hoping for an international agreement to aid them.

Others members of the coalition include Christian Dior, the Federation of Swiss Watch Manufacturers, General Electric, General Mills, Moet-Hennessy, the French champagne and brandy producer, Puma, the German sporting good manufacturer, Singer and Samsonite.