A huge surge in business inventories and rising exports pushed first-quarter economic growth to a strong 4.8 percent annual rate, an upward revision from the 4.4 percent a year pace estimated earlier, the Commerce Department reported yesterday.

The 4.8 percent growth rate, adjusted for inflation and seasonal variations, was up sharply from the 1.1 percent fourth-quarter rate of increase in the gross national product and was the strongest in almost three years. However, since so much of the rise in output went into business inventories rather than into consumption or other investment, most analysts expect the economy will not grow so heartily this quarter.

A much smaller rise in business inventories and cuts in auto production are expected this quarter, analysts said. As a result, forecasts for growth in the April-June quarter generally range from less than 1 percent to about 2 1/2 percent.

The GNP price index rose at a 3.9 percent rate in the first quarter, a figure unchanged from the earlier estimate. The index went up at a 2.7 percent rate in the fourth quarter, with most of the acceleration due to higher energy and food prices.

In a separate report yesterday, the Federal Reserve Board said the nation's factories, mines and utilities operated at 79.6 percent capacity in May. This was a 0.2 percent increase over the previous month. The index had fallen in March and April, largely the result of cutbacks in auto production.

Allen Sinai, chief economist at Shearson Lehman Bros. Inc., said, "The U.S. economy is likely to expand more slowly through the second and third quarters than in the first, when a sizable rebuilding of inventories pushed real GNP up. . . . Except for autos, enough of a pickup in consumer spending and foreign trade to justify the inventory buildup seems to be in process.

"After a pause in the second quarter, when growth is expected at 1 percent to 2 percent, the economy should strengthen," Sinai said.

Some other forecasters, among them Donald H. Straszheim, chief economist at Merrill Lynch & Co., are looking for an even weaker second quarter and a more modest pickup later in the year.

For the year as a whole, Straszheim predicts real GNP will be up 2.2 percent. Real output rose 2.5 percent last year.

The stronger first-quarter performance for real GNP was matched by a large gain in corporate profits, the department said. Corporate profits from current production rose at a 7.8 percent annual rate, or $24.2 billion, to a seasonally adjusted annual rate of $335.4 billion.

Earlier, the department had put the figure at $22.3 billion.

Corporate profits from current production rose at a 3 percent rate in both the third and fourth quarters of 1986 after dropping at a 1.1 percent rate in the second quarter of last year.

Most of the revisions in the first-quarter GNP estimates only accentuated developments shown in previous quarter-to-quarter changes. The swing in business inventories was at an exceptionally large $69.2 billion annual rate after adjustment for inflation.

Since the increase in total real GNP was only at a $43.3 billion rate, business inventories rose more than the nation's total production of goods and services.

Final sales -- GNP less the change in inventories -- declined at a 2.7 percent rate in the quarter after going up at a 4.2 percent rate in the fourth quarter of 1987. However, those figures were distorted by a large change in government purchases of farm commodities as part of its price support program.

Excluding both changes in business inventories and the commodity purchases, final sales were essentially unchanged in the first quarter following a 1.4 percent increase in the fourth quarter, the department said.

Additional information about trade flows caused the department to revise upward its estimate of first-quarter exports of goods and services to show a gain at a $10.9 billion rate, after adjustment for inflation, rather than a $4.6 billion rate. But the added data also showed that the decline in imports was only at a $3.5 billion rate, not the $6.2 billion rate calculated before.

Together, the changes in imports and exports left the improvement in net exports at $14.3 billion, almost as large as the $15.3 billion gain the fourth quarter.

Prior to the middle of last year, the nation's trade balance had deteriorated steadily for several years as imports gained an ever-rising share of purchases from consumers and businesses.

The department made only minor revisions in its estimates for first-quarter consumer spending, which fell at a 1.1 percent rate after declining at a 0.4 percent pace in the fourth quarter. The declines were concentrated in purchases of durable goods, particularly new cars.

However, consumer spending on nondurables has been flat or down a bit since a strong gain in the second quarter of last year. Spending on services, on the other hand, has shown steady increases, going up at a 3.2 percent rate in the fourth quarter and a 4.6 percent rate in the first, the department said.

"Consumer spending is much weaker as households hold back on big-ticket-item purchases, such as cars and homes," Sinai said. "But spending for services and nondurables still is strong enough to support the expansion."