The Army's top commanders have been ordered to find ways to halt "a disturbing trend" in the disciplining of black soldiers.

Gen. Bernard W. Rogers, Army chief of staff, has asked the commanders to determine why black soldiers proportionately receive harsher punishments than do whites and to "eliminate any discriminatory handling of soldiers."

In a letter released yesterday, Rogers said "black soldiers receive disproportionate numbers of punitive discharges, are overrepresented in confinement facilities and are charged with more serious offenses per 1,000 soldiers than white soldiers."

The trend was first spotted in an Army assessment of equal opportunity in 1976. A more recent assessment, released in April, found "these trends are worsening." Rogers said, adding that this "demanding immediate individual and collective attention."

The general tone of that assessment was upbeat. It claimed "significant progress" was being made in racial relations in the Army and that the number of blacks in uniform had increased by more than 50 percent since the draft ended in 1972.

Not only is the percentage of blacks enlisting increasing, but the percentage of those signing up for a second tour is substantially higher than for whites, 47.8 percent compared with 29.5 percent, the report said.

Although the survey found that some soldiers thought race relations in their units had deterioted from 1976 to 1977, the majority "felt that the racial situation had remained about the same," the report said.

"The major areas of concern," it said, are "the disproportionate number" of disonorable and bad conduct discharges given to blacks, "racial imbalances" in job specialties and a shortage of black officers in National Guard and reserve units.

While blacks comprised 26.4 percent of the Army's enlisted force in 1977, they made up 51 percent of the service's prisoner population.

Blacks are underrepresented in 18 fields, the report said, with the most severe shortages in law enforcement, electronic warfare equipment mainenance, the Army band, communications and signal intelligence.

Meanwhile, the report added, "enlisted blacks hold more than their share of jobs in the petroleum supply, food services, wire maintenance, telecommunications and audio-visual fields."

Rogers instructed the commanders of all major bases to examine "the scope of the problem" in their commands and "to identify specific relationships or underlying causes which lead to punitive actions against black soldiers."

He called on senior generals "to use more imagination" in dealing with "this persistent problem area." However, he stressed that affirmative action programs are not intended to reduce Army standards of discipline or conduct.