The U.S. Justice Department has filed a lawsuit against Florida to stop officials from purging non-citizens from the state's registered voter list.

The lawsuit, filed Tuesday, alleges state officials are violating the National Voter Registration Act, which prohibits them from removing people from voter registration lists within 90 days of an election for federal office. The Justice Department says Florida is using “inaccurate and unreliable” information to identify ineligible voters.

Florida officials claim the purge is necessary to protect the integrity of the voting process. They say they have identified at least 2,700 registered voters who may not be U.S. citizens. Florida sued the federal government Monday to seek access to a Department of Homeland Security immigration database so it can compare those names against Florida's list of registered voters.

But critics say it is an attempt to keep minorities, who tend to vote Democratic, from participating in the November presidential election.

Florida is considered a key battleground state between likely Republican nominee Mitt Romney and incumbent Democratic President Barack Obama. Mr. Obama carried the state in the 2008 election.

Florida is scheduled to hold its congressional primary election on August 14