Brazilian President Jose Sarney tonight introduced a series of measures designed to cool a fever of middle-class consumerism that threatened to undercut his inflation-beating Cruzado plan.

He also announced infrastructure investments of $100 billion during the next four years to be raised internally, which he said would "prepare us for the 20th century" by leaving Brazilian citizens as wealthy as those in Southern Europe.

Since its introduction in February, the plan -- whose key elements were a total price freeze and the introduction of the cruzado, a new stable currency -- has reduced this year's inflationary expectations from 450 percent to approximately 20 percent. But, Sarney said, "We cannot just lie on the laurels of having destroyed inflation."

Real increases in earnings have produced an unprecedented surge in consumer demand while savings and investment in new capacity remain static.

So, when Sarney introduced his government's target for the next three years during a television address, he also introduced corrective measures in the form of a decreed law to keep the cruzado plan on course.

The key change is a levy, or "compulsory loan," to cool middle-class spending habits. Sarney repeatedly referred to hidden enemies he said had tried to wreck his economic strategy and vowed he would maintain the price freeze by taxing the rich.

"Contributions will be proportional to spending on nonessential goods and services by the wealthy. Brazil's most successful will help redeem millions of less fortunate," he said.

Consumers now will be obliged to hand the government a three-year interest-paying compulsory loan of 30 percent on the price of new automobiles, 28 percent on gasoline, and 25 percent on international air tickets and purchases of foreign currency.

The government argues that, as these price increases are really loans, their effect will not be computed in the monthly cost-of-living index that shows inflation. At the same time, they will serve to throttle back demand and increase government revenue.

Sarney said the loan system would increase national savings by 2 percent of GNP so completing his cruzado plan and ensuring that Brazil avoided further delays in its development.

The money will go to a "National Development Fund," which also will control the finances of state enterprises responsible for the bulk of Brazil's $100 billion external debt.