The prospects for persons seeking employment in metropolitan Washington during the next three months appear slimmer than a year ago, a survey by Manpower, Inc. indicates.

Manpower's survey of local employers in the private and public sector found that 21 percent plan to add to their staffs, down 5 percent from a year ago when a similar poll was conducted.

The recent quarterly survey also found that 11 percent of the Washington area's employers anticipate reductions, while 66 percent plan no changes in staff levels.

Hiring plans nationwide for the second quarter were described as "weak" by Manpower. Overall, only 19 percent of the more than 10,000 employers contacted in the survey said they plan to add employes to their rolls.

However, survey figures aren't seasonally adjusted and the employment outlook in some areas may be more optimistic than the figures indicate, Manpower said.

Nevertheless, "the current employment outlook remains dreary for job seekers, and there seem to be no signs of an upturn in any business sector," said Manpower's president, Mitchell S. Fromstein.

Fromstein added that information gathered in the survey also indicates that summer jobs for students and teachers will be "more limited than in past years."

Manpower, which describes itself as the nation's largest temporary employment services firm, conducts quarterly surveys to measure changes that might occur in the work force.

The Milwaukee-based firm conducts telephone interviews with private and public employers in more than 300 cities.

Its survey of employers in the District found 22 percent planning to enlarge staffs; 23 percent indicated they will reduce their work forces, and 52 percent said they plan no changes. A year ago, only 13 percent said they planned to increase staff size.

Job opportunities in the District are likely to be found in transportation; wholesale and retail trade; services and the finance, insurance and real estate. Employment is expected to decline in the construction area, however.

The outlook is more optimistic in Prince George's County, where 27 percent of employers expect to add to their staffs and 63 percent anticipate no changes; 8 percent expect to cut back.

More job opportunities in the county are anticipated by manufacturers of durable and non-durable goods, employers in the wholesale/retail area and in the services sector. However, construction companies and public administrators project layoffs.

The outlook for hiring in Montgomery County is "slightly less optimistic," with only 11 percent of employers planning to enlarge their staffs, 4 percent planning reductions and 44 percent anticipating no changes.

Job opportunities are likely to be found in the services and wholesale/retail sectors in Montgomery County during the April-June period.

In Northern Virginia, only 10 percent of employers said they plan to add employes and 10 percent expect cutbacks, with 77 percent predicting no change. A year ago 27 percent expected staff additions.

Employment opportunities are expected to be found in the services and wholesale/retail sectors.