WASHINGTON (AP) _ Factory orders rose modestly in March, but the first quarter of 1998 was a soft one overall as Asian financial turmoil dealt a setback to U.S. export sales.

Orders _ a baromter of future production _ increased 0.3 percent to a seasonally adjusted $336.2 billion following a 0.7 percent drop in February, the Commerce Department said today. Orders for the quarter as a whole are down 0.8 percent from the last three months of 1997.

U.S. manufacturers _ particularly the export-reliant aircraft industry _ have been hurt by slack demand in Asian countries. However, the weakness hasn't yet pushed up unemployment or dampened American consumers' confidence.

Even within manufacturing, the impact has been blunted. Companies have been able to keep production levels up because of a big backlog of unfilled orders.

In fact, shipments of factory goods _ a measure of current production _ jumped 0.8 percent to a seasonally adjusted $340.5 billion in March, the third increase in four months. Shipments for the quarter were up 0.8 percent over the October-December period.

The faster pace of shipments, compared with new orders, allowed manufacturers to reduce the backlog of unfilled orders for the third time in four months. It fell 0.8 percent in March to a seasonally adjusted $538.7 billion.

In March, orders were led by a 4.1 percent increase for computers and other office equipment. Overall, durable goods _ expensive items expected to last at least three years _ rose 0.5 percent.

That included a 3 percent rise for stone, clay and glass products, a 1.1 percent rise for communications equipment, a 4.4 percent gain for medical instruments and a 7.9 percent increase for electronic components.

However, orders for aircraft slumped 16.6 percent, on top of a 34.8 percent plunge in February. Orders fell 4.2 percent for primary metals such as steel, 0.1 percent for fabricated metal products. They also declined for electric lighting and wiring and engines and turbines.

Non-durable goods orders were unchanged from the month before. Orders declined for chemicals, but increased for printed materials.