The principals’ union has filed a class-action lawsuit against the Prince George’s County public school system and its Board of Education.

The Association of Supervisory and Administrative School Personnel filed the suit, alleging discrimination based on age and race, on behalf of its 800 members.

The complaint, which seeks $100 million in lost wages and benefits, interests, costs expenses and attorney fees, was filed this month in District Court.

The union alleges that the school system terminated 27 employees in spring 2011 “under the guise or pretext of a reduction in force and/or reorganization.”

The school system “systematically promoted” younger principals over those who were over 40 and subjected older principals to “more subjective and rigorous performance standards,” according to the lawsuit.

Doris Reed, the president of the union, said employees have been “demoralized.”

“You have experienced people who were passed over for promotion, that affects their jobs and therefore affects the children,” she said.

Briant Coleman, a spokesman for the school system, said in an e-mail that the school system has not been served with a complaint by the union.

Reed said the lawsuit will be served on the board this week.