Coca-Cola, the soft drink that has become as much a symbol of America as Uncle Sam, announced today that it is making a comeback in Egypt after 12 years on the blacklist as the drink fit only for imperialists and Zionists.

The return of Coke, while perhaps of minor importance to Egypt's industrial development plans, nevertheless constitutes a highly visibile signal of the new era in relations between the United States and Egypt opened by President Anwar Sadat.

Sam Ayoub, the Egyptian president of Coca-Cola's Middle East operations, drank what he said was the first new-era Coke produced in Egypt as he announced his plans at a Cairo news conference where more of the first batch was served to reporters.

Trucks carrying Coca-Cola bottles are scheduled to roll through the streets of Cairo and Alexandria, Egypt's second-largest city, next Saturday to mark the official resumption of Coke sales in Egypt. It will be the first time the soft drink is sold openly here since Gamal Abdel Nasser expelled the company in 1967 for doing business in Israel.

Zayed Zein, a streetside merchant who sells toiletries, cigarettes and soft drinks in a downtown Cairo shopping gallery, said the return of Coca-Cola is coming none too soon for Egyptian tastes.

"Someone with a coller full of Coca-Cola in the street right over there would be surrounded by thirsty people in minutes," Zein chuckled. "He would be all out immediately. People would drink it all up."

Zein is in a good position to know. He has been selling soft drinks in the same gallery just off Sheriff Street for the last 21 years. Until Nasser ordered it out, Coke was one of his big sellers.

Actually, the demand for soft drinks of any kind in this Moslem country of 40 million inhabitants far outstrips production. Sidewalk merchants and stores occasionally run out altogether during hot spells.

Government and private bottlers turn out about 70 million cases of 24 bottles annually. But parched Egyptians could drink a lot more if glass companies could make enough bottles and if soft drink companies could make and distribute enough sodas. Ayoub estimated the total soft drink market could read 200 million cases a year by 1985.

For foreigners, the attraction is difficult to explain. Vendors in little stalls throughout Cairo sell fresh orange juice, mango juice, guava juice and even lovely red karkadeh juice squeezed from the petals of a flower.

But Egyptians seem to like their drinks sweet and fizzy. This was demonstrated when Israel returned the Sinai town of El Arish to Egypt six weeks ago in a ceremony attended by Egyptian soldiers - many of whom were seen carrying off family-size bottles of Israeli-made Coke as souvenirs.

The attraction of being modern also is a factor, and this is an image Coca-Cola hopes to cash in on. Ayoub predicted that Coke will have half the Egyptianmarket within two years.

But not too modern. Coca-Cola in Egypt will come in slim, eight-ounce bottles without the traditonal curves. Wags suggested that the resemblance to the female form was one step beyond savvy marketing in a country where the Moslem sexual code is still strong.

Coca-Cola is not the first foreign entry into Egypt's soft drink market. Seven-up and Canada Dry's Sport Cola sell a total of about 13 million cases a year. They also plan to increase production to take advantage of the racing demand.

Coke's reentry into the Egyptian market follows five years of negotiations with the government, which controls franchises and sets bottling standards. The bottles will be manufactured by El Nasr Glass and Crystal Co., a government-run firm, Ayoub said.

Sales at first will be restricted to Cairo and Alexandria, with a gradual extension planned into the Nile Delta area by the end of the summer and the rest of the country by late fall, he said. The syrup is coming from overseas for the time being. Within two years, a concentrate plant is to be built at Alexandria.

The product's reentry also marks a significant departure from the Arab blacklist because of the size of the Egyptian market. The list already has shown flexibility, however, and Coca-Cola is sold in Tunisia, Morocco, North Yemen, Somalia, Djibouti, Mauritania and Algeria, Ayoub said.

Lebanon still abides by the list's strictures - officially. But in Beirut, where almost everything is for sale, Coke for years has been available at outdoor cafes. CAPTION: Picture, This eight-ounce bottle will bring a well-known symbol of America back to Cairo. AP