Extra men were assigned to ride the delivery trucks after reported attempts to carry off the precious cargo. Merchants who obtained it legitimately sold it as fast as they could display it. Americans with ties to the company got midnight telephone calls from Cabinet ministers asking for special supplies.

The prizes? Bottles of 7-Up, suddenly the hottest commodity in Egypt.

This country's insatiable thirst for soft drinks, attributable to hot dusty weather, the national sweet tooth and the Moslem ban on alcohol have made 7-Up the most popular American product to be marketed here since diplomatic relations between Egypt and the United States were restored in 1974.

Until June, 7-Up was an unattainable luxury for most Egyptians because it was imported from bottling plants abroad and sold at tourist hotels and restaurants for a dollar.

Then local production began, at an automated plant on the outskirts of the city that turns out 7-Up and Canada Dry's Sport Cola. With the sale price on the street cut to the equivalent of seven cents a bottle, demand exceeded production almost overnight.

"Anything sweet to eat or drink is the best business of all in Egypt," said sales manager Shams Tayeb. His job is not so much to promote sales, he said, as to make sure that all the distributors get their fair share of the limited supply - a task that required the trucks to break out of circles of would-be clients who were trying to carry the drinks away by the case to meet their customers' demand.

The bottling plant is owned by Cairo Beverages and Industrial Co., a privately owned corporation of Egyptian and foreign investors that produces the soft drinks under license. Sources familiar with the corporation's background said the biggest single investor is the former chief of Saudi Arabian intelligence, Kamal Adham, who has extensive business interests throughout the Middle East.

The new plant is already turning out 43,000 cases a day, or about 1 million bottles, and sales manager Tayeb said production would soon be increased to 50,000 cases.

Cairo Beverages is one of the first private operations financed by foreign investors to begin operation under the economic open-door policy proclaimed by President Anwar Sadat after the 1973 Middle East war, and is certainly the first to have any direct impact on the Egyptian masses.

It competes directly with government-owned plants that produce Pepsi Cola and Si Cola, a local brew for which demand exceeds supply despite a reputation for uneven quality.

Economic analysts say that most of Egypt's state-owned industries could not stand direct competition from modern, well-managed private enterprise rivals, but 7-Up and Sport Cola, despite their success, present no threat to their rivals because demand for all of them outstrips their production capacity.

The overnight success of 7-Up surprised even the company's executives, who launched a major publicity campaign on billboards, television and in the movies that turned out not to be necessary.

The Arabic language has neither a "V" sound nor a "P" sound, so improvised letters are used for both in the big 7-Up billboards that have sprouted all over Cairo and on the green bottles that had to be imported from Greece because Egyptian glass factories could not produce enough. As a result, the words "Seven Up" have quickly become part of the local language, as has Pepsi.

Absent from that roster is Coca Cola. Coke is not sold here, nor in many Arab countries, because it is on the blacklist of the Arab boycott of Israel.

The Coca Cola Co. is involved in a project to develop citrus groves on 15,000 acres of desert near the Suez Canal, and is understood to be ready to make major investments in the Arab world if its name is removed from the boycott list.

"There's plenty of room for them too," one industry export said. "The gap in the market here between production and demand is still unbelievable.