The Soviet Union tonight launched its long-awaited crackdown against alcoholism with a series of tough measures, many aimed at drinking among the young.

The package, summarized tonight by the Soviet news agency Tass, will raise the drinking age from 18 to 21, delay the opening of liquor stores on working days by three hours, start a gradual reduction of production of vodka and other strong beverages in 1986, and completely ban sweet and potent fruit-based alcoholic drinks by 1988.

Stiff penalties will be given to those caught "in a drunken state in public places," and drunk drivers will get hit with even higher fines -- 100 rubles, or about $130 at the official exchange rate -- as well as the loss of their driving license for one to three years, Tass said.

Alcoholism is a major -- and growing -- health and social problem here, in addition to being one of the single biggest drains on labor productivity. It is linked to important trends such as the decline in male life expectancy from 67 to 62 in the last 20 years and is considered the leading cause of accidental deaths, crime and divorce.

Additional measures announced were directed at the causes and consequences of the Soviet Union's drinking problem -- for instance, improving recreation facilities for the young and improving treatment of alcoholics.

This many-sided approach is necessary to combat the "great social harm of alcoholism," said an accompanying resolution by the Central Committee of the Communist Party. "The abuse of alcohol is so far quite often not regarded as an immoral, antisocial conduct . . . . The force of the law and of public opinion is not applied to drunkards in full volume."

The new measures -- expected to be outlined more fully in Friday's newspapers -- culminated a two-week buildup in the press and on television, as the Soviet media responded to the ruling Politburo's call last month for a full-fledged "struggle against alcoholism."

The alcoholism campaign is part of Soviet leader Mikhail Gorbachev's push for greater discipline and accountability in the work place. And the new laws represent his first effort to put his program into effect.

Because the alcoholism problem is keenly felt at all levels of society, Gorbachev's initiatives could be his first real test before the public.

Tonight, as he continued a tour of Leningrad, Gorbachev told a group of people on a street that drunkenness was a critical problem for the country and that "more severe" steps were needed, and would be published Friday. The crowd around him reacted eagerly.

The comments on alcoholism were typical of the candor displayed by Gorbachev on the Leningrad trip, according to a half-hour film shown on tonight's news program. Unlike other televised tours by Soviet leaders, on this trip Gorbachev's conversations with workers and students were recorded, giving a glimpse of the leader's adroit style, much like that of a politician on a campaign swing.

The package announced tonight tries to compensate for restrictions in alcohol production with "sweeteners." For instance, the production of soft drinks is supposed to start increasing in 1986, the year that output of strong alcoholic drinks starts to decrease gradually.

Likewise, when fruit-based alcohol -- which unofficial sources tonight defined as liqueurs of more than 18 percent alcohol, not wine or cognac -- is banned in 1988, the production of juices, jams and fresh fruit is expected to increase.

Anyone, including parents, giving drink to a minor will be dealt with particularly harshly under the new package. Tass said sentences for the offense will range from imprisonment to corrective labor.

The alcoholism problem is one that virtually everyone recognizes here. It is not new; the Russians' love of strong drink was remarked on by travelers in the 18th century. But official and unofficial statistics acknowledge that alcoholism in the Soviet Union has been getting worse: More and more people drink, they drink at a younger age, they drink when they work, and often when they drink, they drink to get drunk.

As the media campaign built up in the past few weeks, rumors swept the city. People talked of rationing, of doubling prices, of bans on alcohol at official functions and of automatic firings for people caught drunk or drinking at work.

Some people even expressed hopes -- far-fetched, they would admit -- for a complete prohibition or "dry law," such as one that was in effect from the beginning of World War I until 1924.

But for all the growing public disgust with excessive drinking, there is also strong public reluctance to condemn the practice.

Railing against the evils of portvin, a sweet wine with high alcoholic content, one Russian agreed it should be banned. "But not vodka," he said, ticking off the ailments for which vodka is considered a cure. "Vodka is healthy."

This week, as the nation recovered from its second public holiday in less than 10 days and the hangovers that went with it, the media campaign worked at overcoming any cultural resistance to the crackdown by stressing the evils of drink and advocating "dry" weddings and teetotalers' clubs.

One day, a Moscow fire captain was on television blaming alcoholics for starting most fires. The next day, the Communist Party newspaper Pravda linked the crackdown on drinking with the push for higher moral standards among party members.

Another paper issued a plea for less drinking at official banquets, and a third wrote about a theater group staging plays praising the merits of abstinence.

Managers have written to complain about drinking among the work force. Other reports noted that managers overlook the problem and allow drunkenness because they do not want to lose workers.

Pravda this week carried an article by an economist who noted that labor productivity falls after paydays and weekends because of drunkenness.

In addition to stiffer sentences for law-breaking drinkers, the author advocated other remedies -- filling leisure time with other pursuits, such as access to private garden plots where people do "useful work and improve their health."

Boredom, loneliness brought about by rapid urbanization, frustrations of working and coping in an economy plagued by shortages and the lack of varied entertainment have all been cited as causes of the growing rate of alcoholism here.

Statistics about alcoholism in the Soviet Union are incomplete and, in some cases, shielded. But the dimensions of the problem are acknowledged by both experts and casual observers.

In the work place, drinking is the plague of managers. At just one factory in the Siberian region of Irkutsk, 500 working days a year were lost to drunkenness, according to one article.

Furthermore, the problem has been spreading among women, teen-agers and, in some cases, even children.

An article published in 1983 said the amount of liquor consumed annually in the Soviet Union has risen to about 17 liters per person 15 years old or older.

According to Census Bureau statistics, Americans consumed 2.8 gallons, or about 10.5 liters, of distilled spirits per capita in 1982.

The number of deaths from acute alcohol poisoning has risen from 12,500 in the mid-1960s to 51,000 in 1978, according to studies done in the West.

According to Vladimir Treml of Duke University, a leading expert on Soviet alcohol consumption, 200 people died in 1976 from drinking antifreeze, 1,000 from imbibing various cleaning fluids and 5,000 from ingesting a vinegar concentrate held to be a remedy for hangovers.

The state, as the producer of alcohol, makes a profit from the public's affinity for it. Recent estimates put the government's earnings from alcohol at $72 billion, or 10 percent of the national budget.