A spokeswoman for the Civil Rights Division of the Justice Department said Friday that the department will take under advisement any request filed by Maryland Republicans and a grass-roots voter rights group to investigate if Gov. Martin O’Malley (D) and Democrats racially gerrymandered a congressional map for party gain.

The state’s GOP and Fannie Lou Hamer Political Action Committee, a small Prince George County-based organization, have joined forces to challenge the map. It will create Democratic majorities in seven of the state’s eight congressional districts, in part by splitting majority-minority Montgomery County into three mostly white voting districts.

The groups have not yet filed an official request with Justice, but in public comments on Thursday they accused Maryland Democrats of violating the 1965 Voting Rights Act and called on Justice to investigate.

Asked about the public comments, DOJ spokeswoman Xochitl Hinojosa wrote in an e-mail to The Post: “The department will review the request and we decline further comment at this time.”

Maryland’s General Assembly passed the plan on Thursday, and an hour later O’Malley signed it into law.

Minutes before the signing ceremony, O’Malley’s office released a letter from Attorney General Douglas F. Gansler (D) stating that he found “no reason” to believe the congressional redistricting plan “constitutes a racial gerrymander” in violation of the 14th Amendment.

Across the state, the new map divides minorities among multiple districts, preventing the creation of a third congressional district dominated by minorities. Critics including Rep. Donna F. Edwards unsuccessfully urged that such a district was natural in part of Montgomery County, which the 2010 Census revealed is 51 percent minority.

State lawyers and members of the governor’s redistricting commission contend that O’Malley’s plan is legal and will withstand challenges because it maintains two majority African American districts.

Radamese Cabrera said the Fannie Lou Hamer PAC intends to file the request with Justice and pursue litigation in federal court.

The legal battles are likely to thrust Maryland onto the leading edge of a next generation of civil rights litigation being spawned by the 2010 Census and congressional redistricting.

For nearly 50 years, the Voting Rights Act has mostly been used to force states to weigh whether districts are drawn to allow blacks to pick the candidates of their choosing. But with an increasingly diverse population, it is morphing into an ever more complicated and nuanced test of minorities’ voting rights, election law experts say.

Fast-growing Hispanic and Asian communities, as well as more mingling of minority and white neighborhoods, are forcing states, federal courts and the Justice Department to consider whether minority voters in different corners of the country have more in common with one another than with white voters and whether they should therefore be lumped together for elections.

Redistricting litigation is pending in 22 states, and in nearly half of those — including many of the largest states critical to control of the House of Representatives — arguments about how to treat amalgamations of African Americans, Hispanics, Asian Americans and other minorities are expected to become the focal point of courtroom battles, experts say.

Efforts by Democrats in Maryland to use redistricting to gain advantage in Congress are not unlike those Republicans have pursued in many other states.

Democrats hope the plan will unseat 10-term Rep. Roscoe G. Bartlett (R). His traditionally conservative 6th Congressional District in Western Maryland will pick up nearly 350,000 mostly Democratic voters in Montgomery County.

“Marylanders have a right to fair district lines that represent true communities of interest rather than partisan political interests,” said Maryland Republican Party Chairman Alex Mooney.