The U.S. Department of the Interior has filed a counter-lawsuit seeking to stop the Cherokee Nation of Oklahoma from denying tribal citizenship and other rights to the descendants of slaves once owned by some tribal members.

The counterclaim, filed in U.S. District Court in Tulsa on Monday, also seeks an injunction and a declaratory judgment that an 1866 treaty "provided Cherokee Freedmen and their descendants with 'all the rights of native Cherokees,' including the right to citizenship in the Cherokee Nation."

The filing is the latest chapter in a long-running dispute between the descendants of slaves, known as freedmen, and the second-largest tribe in the United States.

The freedmen sued the Cherokee Nation after members voted in 2007 to amend the tribal constitution to restrict citizenship to those who could show at least one ancestor was listed on the Dawes Rolls. A federal court order has kept the citizenship of about 2,800 descendants intact pending the lawsuit's outcome.

Some Cherokees and members of other tribes in the southeastern U.S. were slaveholders, and were allied with the Confederacy during the Civil War. After the war ended and slavery was abolished, the Cherokee Nation and the federal government signed the Treaty of 1866, which said the freedmen and their descendants "shall have all the rights of native Cherokees."

The Interior Department wants the court to declare that the tribal constitution amendment is inconsistent with the Treaty of 1866. The tribe has argued that the treaty didn't give the freedmen perpetual citizenship rights and that, as a sovereign nation, it has a right to alter its constitution.

In a statement issued on the tribe's website, Principal Chief Bill John Baker said the claim will allow the case to move forward.

"We will have everyone at the table and all issues will be presented so we can get a definitive ruling," he said in the statement.

Marilyn Vann, president of the Descendants of Freedmen of the Five Civilized Tribes, called the filing "very positive."

"I'm very pleased with the filing," Vann said Wednesday. "I think they batted it out of the park."

An attorney representing the freed slaves' descendants, Jon Velie, told The Oklahoman the federal government could have requested the case be dismissed for technical reasons, but chose to fight it out in court.

A hearing on the counterclaim hasn't been scheduled.