At Clara's, where Hungary's elite has long done its shopping for fine fashions, the clients are no longer just the famous and powerful friends of Clara Rothschild, the former manager who gave the store her name, but a swelling class of people popularly tagged the "new rich."

A few doors up Vaci Street, Budapest's main consumers' thoroughfare, the Ofotert camera store sells Japanese-made Nikons and Canons for the equivalent of five times the average monthly salary, and still the store cannot keep enough in stock to meet demand.

Across the Danube River at one of the city's few indoor tennis facilities, the license plates on the Mercedes and BMWs show the cars belong not to tourists, foreign diplomats or government officials, but to private Hungarian citizens.

In the nearby hills of Roszadomb, a residential district with Budapest's poshest homes, the lumber and brick foundations of numerous villas under construction crowd in among the aging grand dwellings of an earlier era.

Such sights attest to an expanding corps of moneyed Hungarians, people cashing in on an economic reform that has finally made getting rich officially acceptable.

Theoretically under communism, no one is supposed to be much richer -- or much poorer -- than anyone else. But after years of seeing initiative weakened and productivity lowered by paying workers the same no matter how much they produced, Hungary's communist party is the first in the Soviet Bloc to revise the principle of equality and boldly declare that people ought to earn as much as they are worth on the job.

This decision was made at a session of the policy-making Central Committee last year and is expected to be reaffirmed at a meeting this week of a once-every-five-years congress of party delegates. Equality of opportunity, not simple equality, is the new catch phrase. Hungarians are being asked to accept wider income differentials -- the widest in Eastern Europe -- as a natural outcome of introducing better material incentives and market mechanisms.

But old lessons die hard. The conspicuous consumption of a growing number of affluent Hungarians is feeding envy and resentment among poorer people brought up believing in the old equality slogan.

A stagnant economy has aggravated the tension. While flourishing Budapest boutiques, some bearing such western trademark names as Pierre Cardin and Foto Quelle, cater to those with money, the overall standard of living has eroded in the last five years. Real wages slipped about 2 percent in 1984, making those who are less well off -- unskilled workers, pensioners and young families -- more bitter about those who are prospering.

Communist authorities are anxiously watching the scope of this backlash, recalling that antireform groups capitalized on such negative sentiment in the early 1970s, effectively stalling for six years the economic reform plan introduced in Hungary in 1968.

Articles critical of growing income disparities have been appearing in the state-controlled press. "It is basically jealousy clad in socialist conservatism," said a senior western diplomat.

Nevertheless, the political repercussions of these attacks are worrisome to people like Katalin Mogyoro, a sociologist and radio journalist who has studied the problem and debated the critics. "My articles answering the criticism were not meant to be in favor of the rich but of the reform," she explained in an interview. "Much was being publicized against the rich, and I was afraid this could undercut the reform effort."

Actually, many of those considered rich in Hungary would not be rich in the West. Just having a house, a car and a few western products is a mark of affluence in a country where the average worker earns the equivalent of $100 a month, housing is in desperately short supply and goods from the West are a luxury.

In one respect at least, the wealthy here are the same as everywhere else: They rarely confess how rich they are. In the absence of an income tax and the obligation to report total earnings, government officials are left guessing at the amounts being privately amassed and at the number who qualify as rich.

According to specialists on the subject, the new rich is a heterogeneous class and its sources of wealth vary. Some inherit a treasure. Others, particularly lawyers and doctors, get rich taking tips on the side -- a standard but unofficial practice in Hungary. A few people have prospered by inventing something. Some journalists, engineers and entertainers are fortunate enough to work abroad, earning hard western currency rather than softer Hungarian forints. A small number of ambitious entrepreneurs have taken advantage of recent regulations permitting the operation of private firms on a broader scale.

All these methods are more or less legitimate. But huge profits are also being made by price gougers, profiteers selling scarce items such as auto parts, or middlemen in the fruit and vegetable trade who add little of value but pocket a bundle. Everyone seems in agreement that money earned this way should be policed closely and discouraged.

Hoping to put some sort of brake on the rich, the government is developing an income tax in consultation with experts at the International Monetary Fund. A value-added tax on purchases is also being considered to dampen conspicuous consumption. But authorities say the tax schemes won't be ready for a few years.

"It's a touchy issue," remarked Janos Hoos, a Central Committee member and one of Hungary's chief economic planners. "We don't want to create an atmosphere in which people who are productive and earning a lot would feel their activities are not desired."

In the interim, officials are focusing on several other measures to diffuse the new rich issue -- promoting more competition in the private sector, for instance, and promising more aid to poorer groups in the form of increased payments and the introduction of western-style social workers at the community level, according to Hoos.

At the same time, authorities are trying to soak up some of the wealth held in private hands by developing a bond market -- a novelty in Eastern Europe -- and by encouraging investment in new small enterprises.

Hungary's economic reformers recognize that the only lasting answer to public reservations about their program is a general improvement in the country's economic performance. Without it, the resentment of many Hungarians toward the new entrepreneurs is almost certain to grow.

Mindful of this, the government has begun to lift some of the austerity measures it had in place to push the trade balance back into surplus and pay off some of the foreign debt. The coming five-year plan foresees moderate growth, a welcome relief for many after five years of stagnation.

"The situation has become somewhat tense because as a segment of society became worse off, another group has clearly become better off," Hoos said. "If we can bring the whole of society into better conditions, then the problem will ease."