The Justice Department filed a lawsuit Friday against Alabama and its secretary of state, arguing that an effort to remove voters from state rolls was taking place too close to the Nov. 5 general election in violation of federal law.

While states are allowed to clean up their voter registrations ahead of an election, federal law says that must happen more than 90 days before an election.

Alabama’s Secretary of State Wes Allen on Aug. 13 announced a crackdown on what his office called “noncitizen voters,” saying that more than 3,500 people who were registered to vote had been issued noncitizen identification numbers by the Department of Homeland Security. His office did not specify when those voters had received the ID numbers.

The Justice Department said Friday that the voter roll purge announcement in Alabama took place 84 days before the Nov. 5 election and therefore violated the National Voter Registration Act.

“As Election Day approaches, it is critical that Alabama redress voter confusion resulting from its list maintenance mailings sent in violation of federal law,” the Justice Department said in a news release announcing the lawsuit. “Officials across the country should take heed of the National Voter Registration Act’s clear and unequivocal restrictions on systematic list maintenance efforts that fall within 90 days of an election.”

Allen’s office declined to comment on the lawsuit, citing the pending litigation, but the secretary of state said in a statement that it’s his “Constitutional duty to ensure that only Americans vote in our elections.”

NBC News previously reported on concerns from voting rights advocates and attorneys who argue that measures which focus on preventing noncitizens from voting — an illegal and rare occurrence — mainly affect naturalized Americans.

In the Aug. 13 announcement, Allen’s office said he acknowledged that it was “possible” some of the 3,500 people had since become citizens and now eligible to vote.

The DOJ said Friday it had already found that some of the 3,521 individuals Alabama identified as having a noncitizen identification numbers have since become naturalized citizens, granting them the right to vote in elections.

Allen told NBC News in August that affected eligible voters could take steps to address the matter on Election Day.

“This update can be done by completing a form or going online. This step may be accomplished even at the polling place on election day,” he said in a statement at the time.

Noncitizen identification numbers are assigned to immigrants by U.S. Customs and Immigration Services to track their immigration files, employment eligibility and visa applications, among other things. Permanent residents who then become naturalized citizens will have had a noncitizen identification number at some point.

The DOJ lawsuit comes as Alabama kicked off its general election this month, becoming the first state to start sending out mail ballots on Sept. 11.