The nation's unemployment rate edged up slightly last month while industry payrolls grew less rapidly than in March, indicating the economy may be slowing somewhat from its earlier pace, the government reported yesterday.

Labor Department figures showed the number of persons out of jobs reached 5.8 percent of the work force, virtually unchanged from the 5.7 percent recorded in March. Payroll levels rose a scant 72,000 jobs, after soaring 422,000 in March.

The report was clouded by figures from the department's monthly household survey showing the total number of jobs in the economy plunged by 668,000-the sharpest drop since 1968-conflicting dramatically with the payroll measure.

However, analysts at the bureau of Labor Statistics said the 668,000-job figure probably was a fluke. They said the April sampling was distorted by the impact of the truckers' strike, religious holidays, floods and tornadoes.

Janet L. Norwood, acting BLS commissioner, said the overall figures "show some slowdown in employment growth." But she warned economists may have to wait for May or June data before telling whether a downturn has begun.

A slowdown in new job growth would be welcomed by the administration. New hiring in the industrial sector was so frenetic in February and March that some Carter policymakers had feared the economy might be overheating.

The past few months' reports on wholesale prices, the latest of which was made public on Thursday, have shown sharp increases in industrial prices, in part because of excess demand. The April index was up 0.9 percent.

Top Carter administration economists had been urging the Federal Reserve Board to raise interest rates to cool the overheating. The Fed has begun nudging interest rates up, but it's too early to tell how far it will go.

The figures came as, separately, the Council on Wage and Price Stability predicted that food prices will not rise significantly in May, "with the possible exception of vegetables and beef."

In another of its monthly food price reports, the agency said the recent drop in farm prices will lead to some moderation in food prices in April and May. But it warned that beef prices will continue to rise during May.

The suspicion that the employment decline was an aberration was bolstered by accompanying figures showing a companion 603,000 decline in the size of the labor force-a figure that counts both job-holders and job-seekers.

Declines of that magnitude often result from flaws in the sample that month. The April survey was taken during a week that included the truckers' strike, Good Friday, Passover and adverse weather in many areas.

The sampling problems also distorted figures on hours worked and on weekly earnings. The closely watched index of aggregate weekly hours, a key indicator of economic activity, plummeted 1.7 percent, after soaring in March.

The department's hourly earnings index for rank-and-file production workers rose 0.6 percent in March, but this, too, was distorted by the sampling week. Analysts said it could be months before any trend becomes clear.

For all the confusion surrounding the employment figures, the unemployment rates for various categories of workers remained virtually unchanged in April. Jobless rates for adult men and women held steady at March levels. CAPTION: Graph, no caption, The Washington Post