Maryland election officials are being sued by a group of state residents who say the state's newly adopted congressional redistricting map discriminates against blacks and other minorities.

The lawsuit, filed in federal court on Thursday, charges that gerrymandering was used to underrepresent minorities in the state's new map, which the General Assembly approved in a special session last month. The suit names as defendants Linda H. Lamone, the state administrator of elections, and Robert L. Walker, the chairman of the State Board of Elections.

"This plan intentionally discriminates against minority groups by drawing districts that fracture minority communities for the benefit of white incumbents," according to the lawsuit, which nine citizens filed jointly in U.S. District Court in Greenbelt.

The lawsuit argues that Maryland's growing population of black, Asian and Hispanic groups justifies the creation of a third minority-majority district. It also charges that the redrawn districts deliberately dilute blacks' voting power statewide "for the benefit of white candidates."

Maryland Attorney General Douglas F. Gansler has reviewed the map and declared, in a letter to Gov. Martin O'Malley, that he found "no reason" to believe that it "constitutes a racial gerrymander."

"The governor's map complies with the letter and the spirit of the law," said Raquel Guillory, spokeswoman for O'Malley. "We are confident it will stand up to legal challenges."

The suit also challenges Maryland's method of counting prisoners, for redistricting purposes, at their last known address rather than the federal or state prison where they are currently being held.

"We welcome the lawsuit and we think it's the right move to try to stop what we view is a real radical, radical breakup and dissection of minority communities in Governor O'Malley's map," said Justin Ready, executive director the Maryland GOP, which is supporting the suit. "We are joining the Fannie Lou Hamer PAC and lots of other citizens in the state to stand up and say that redistricting should not be based on incumbents and partisanship."

The suit is expected to cost the plaintiffs a quarter-million dollars, according to Radamese Cabrera, spokesman for the Fannie Lou Hamer Political Action Committee, a black-majority voters rights group that helped mobilize the plaintiffs.

This is the second lawsuit filed against Maryland's new congressional map.

The first, brought by Smithsburg resident Howard Gorrell, claims the new districts illegally lump together Western Maryland's farming communities with urbanized, Democrat-controlled areas of Montgomery County.