The increasingly bitter tone of the debate between Montgomery County's new school board majority and several black community groups has prompted the U.S. Justice Department to send an official to try and mediate the dispute.

Henry Mitchum, of the Justice Department's Community Relations Service, said yesterday he has thus far met several times with the board and black county leaders.

The controversy first erupted last month when the four conservative members of the seven-member board attempted to rescind the requirement that all 12,000 school employes take a specific black culture course.

That board meeting turned into a shouting war between the conservative board members and dozens of angry black parents who protested that they were not given a chance to comment on the action.

Several groups, including the Montgomery County chapter of the NAACP and the county's Organization of Black Parents, since have denounced the board's new majority as "racist" and "injust," and announced plans to picket future board meetings.

In reaction to the outcry the board announced last week that it would hold a public hearing on the black course Jan. 16, before taking final action.

Mitchum said yesterday his role in conciliating the dispute is "very lowkey." He said the purpose of the Justice Department community relations service is to find areas of compromise in racial disputes and to lessen the likelihood of verbal or physical confrontations.

In a related development, board president Marian Greenblatt promised to make "a full public disclosure" of school spending after an NAACP member stood up during the board's all-day meeting Tuesday and demanded to know how much money the board is spending on the legal fight over School Supt. Charles M. Bernardo's contract renewal.

Hanley Norment, the NAACP member, also wanted to know how many board members planned to attend national education meetings next month and how much money was allocated by the board for out-of-state travel.

Greenblatt said a disclosure would be made this week.