A civil rights group on Wednesday filed a lawsuit against the state of Alabama, charging that its law requiring voters to have photo identification will prevent thousands of residents from casting ballots.

The National Association for the Advancement of Colored People (NAACP) and Greater Birmingham Ministries filed the federal lawsuit, which cites state estimates that at least 280,000 people will be disenfranchised as a result of the law.

The complaint says that because those affected are disproportionately black and Hispanic, the law amounts to intentional racial discrimination.

The state attorney general's office had no immediate comment.

A requirement that went into effect last year requires voters to show valid, state-issued photo identification at polling stations. The state's Republican-controlled legislature approved the law in 2011, saying it was meant to prevent fraud.

Last month, Alabama agreed to change its voter registration practices following a Justice Department investigation that found "widespread noncompliance" with the National Voter Registration Act. Justice Department investigators said Alabama had failed to apply information from driver's license applications to voter registration.

In March, the Supreme Court undid a lower court ruling in favor of Alabama's latest redistricting plan. The lower court had ruled that the redistricting plan was not discriminatory, although black and Democratic voters were disproportionately represented in a handful of districts.

Al Jazeera and The Associated Press