The union representing District of Columbia firefighters threatened yesterday to file suit against Mayor Marion Barry if he accepts a directive from the city's Office of Human Rights that the fire department fill 60 of 70 vacancies with members of minority groups.

Officials of the union also complained to U.S. Rep. Stan Parris (R-Va.), the second-ranking Republican on the House District Committee, who said later that he was "outraged at what appears to be a clear intention of the District to put the issue of minority rights ahead of [hiring] qualifications."

Meanwhile the lawyer for the two black firefighters organizations that filed the complaint leading to the directive contended that the measure did not go far enough in ordering action to correct longstanding racial imbalance in the department.

"We expected to be higher," lawyer Joan Burt said. "The findings demonstrated tht there was discrimination . . . The case is not yet over. The government will have to respond."

The crossfire of complaints appeared to heighten the political atmosphere in which Mayor Barry will have to decide how to respond to the directive, which does not carry as much weight as a court order but does mark the first time the city has been directed to adopt hiring quotas.

Although the human rights office enforces the city's antidiscrimination laws in hiring, public accommodations and other areas, in this instance it also acted in another capacity -- that of the chief internal administrative judge regarding equal employment opportunity for city employes.

Barry declined repeatedly yesterday to comment on the directive, as did City Administrator Elijah B. Rogers. As the top administrator in city government, Rogers would have to hear any appeal of the directive. Fire Chief Norman Richardson and Pesonnel Director Jose Gutierrez, who would have to initiate any appeal, were unavailable for comment.

Since his election three years ago, Barry has strongly criticized racial imbalance in the 1,410-member fire department. The city's population is 70 percent black. The fire department staff is 63 percent white.

Earlier this year, Barry refused to hire 24 applicants offered firefighter jobs because 23 of them were white. Under pressure from Congress and public criticism, he reversed himself, however, and hired those persons but placed a freeze on any future hiring while he studied the civil service exams and procedures used in the department.

Barry, whom many consider to be already running for reelection, narrowly won the crucial Democratic primary in 1978 with strong support in the city's white neighborhoods and with the backing of the unions representing both police and firefighters. Since then, both labor groups have criticized his actions affecting their members.

Earlier this month, the mayor announced changes in the hiring procedures for city police officers, altering standard civil service methods in an effort to increase the number of blacks, Hispanics and women. That move was sharply denounced by the police union. Yesterday, the firefighters union joined the refrain.

"We want the fire department to stick to the merit principle," said William E. Mould, president of the union, Local 36 of the International Association of Firefighters. "If we lose that, we lose everything."

In Monday's order, the Office of Human Rights told the fire department to fill its 70 vacancies from a pool of 958 persons who passed a written exam last November. Sixty of those persons should be members of minorities, the directive stated.

Mould, whose 990-member local includes about 200 black firefighters, acknowledged yesterday, "We have to increase our minorities in the department."

But, he said, pointing out that the last three fire chiefs -- Burton Johnson, Jefferson W. Lewis and Richardson -- have been black, the problem was not racial. "If it is [racial]," Mould said, "it is black against black, not white against black."

Mould criticized the city government's handling of both fire and police issues. "We definitely should go back under the federal system. The District government has police and fire in shambles."

Representatives of the two organizations that brought the complaint, the Progressive Firefighters Association and the Black Fire Officers Association, could not be reached for comment yesterday.

Guitierrez and Richardson have up to 15 days to request an appeal of the directive. If none is asked, the city will be expected to comply with the quota outlined and with an accompanying directive to establish within 30 days an affirmative action program for the department.

In the event of noncompliance, the human rights office could ask the city's Human Rights Commission to seek a court order compelling the city to implement the directive.