The number of new houses and apartment buildings completed in the United States fell by 13 percent in March after rising 4.2 percent in February, the Commerce Department reports.

Economists expect homebuilding to remain sluggish throughout this year, mainly because of rising interest rates.The March drop left housing completions at a seasonally adjusted annual rate of 1.39 million units, the department said. The March rate was also 13 percent below the March 1988 rate of 1.60 million units.

Single-family homes were hardest hit, with completions dropping by 17.3 percent in March to a 983,000-unit annual rate. Buildings containing two or more units slipped 1 percent to a 410,000-unit-a-year rate.

Regionally, the steepest decline in overall completions was in the Northeast, where they fell 33.9 percent. Completions also fell 6.6 percent in the Midwest, 7.8 percent in the South and 9.8 percent in the West.

Before seasonal adjustment, the actual number of new single-family and multi-family homes completed in March was 101,600 units, compared with 104,400 in February.

The housing sector has been one of the weakest components of an economy that appears to be slowing down after more than six years of expansion. Housing starts, a more reliable and widely used measure of the home building industry's health, fell 5.4 percent in March.