The National Rainbow Coalition Inc. and the Citizenship Education Fund filed a lawsuit yesterday in U.S. District Court in an effort to restore more than 30,000 names to the D.C. voter registration roll.

The D.C. Board of Elections and Ethics is required by law to drop voters who have not voted over a four-year period.

It has purged 31,100 voters' names in 1989 and 1990, according to a spokesman for the election board.

The two groups filing the lawsuit allege that the purge discriminates against blacks, Hispanics, the poor, the young and the handicapped and punishes registered voters for not voting in previous elections, said Frank Watkins, a spokesman for the Rainbow Coalition.

In a joint statement, elections board Executive Director Emmett H. Fremaux Jr. and General Counsel William H. Lewis said yesterday that the board for some time has maintained that the nonvoting purge is "antiquated," of "questionable constitutional merit" and "both unnecessary and redundant" as a means of maintaining an accurate voter registration roll.

Fremaux and Lewis said they plan to recommend that the board voluntarily enter into a consent agreement that will allow qualified voters whose names were purged to vote in the September primary and the November general election.

The Rainbow Coalition and the Citizenship Education Fund, a voter registration group that is an offshoot of the coalition, also have called upon the D.C. Council to adopt emergency legislation on Sept. 15 to do away with the rule that cuts off voter registration 30 days before the November election.

The cutoff is part of an administrative procedure to allow for the computerization of new voters, according to a board spokesman. If the council seeks to eliminate the cutoff, the board will address the issue in testimony before the council, Fremaux said.