TULSA (AP) — A recent vote by the Cherokee Nation to revoke the membership of descendants of freed slaves might not have been legal, according to the leader of the federal Bureau of Indian Affairs.

The Tahlequah-based tribe disagrees with that assessment, however, and a tribal spokesman predicted that Congress will reject an effort by one of its members to stop the tribe from receiving federal funds, the Tulsa World reported from its Washington bureau.

The two sides are debating the tribe’s right to enforce a 2003 tribal constitutional amendment and its March 3 vote to remove the descendants of the tribe’s freed slaves, known as freedmen, from tribal rolls.

Carl Artman, who heads the BIA, told U.S. Rep. Diane Watson, D-Calif., in a letter that the U.S. Interior Secretary must approve the 2003 amendment before it can take legal effect. The letter also said the BIA has taken no action on the March vote.

“We are concerned about the ramifications this will have on the Freedmen of the Cherokee Nation and will continue our careful evaluation of all facets of this matter,” Artman wrote in the letter, which came in response to an earlier letter from Watson and other members of the Congressional Black Caucus, who have called the Cherokees’ vote discriminatory.

A spokesman for Watson said the congresswoman is drafting a bill to keep the Cherokee Nation from receiving millions of dollars in federal funds. She wants the BIA to require the tribe to restore citizenship to the freedmen descendants.

Cherokee Nation spokesman Mike Miller said only the tribe, and not the BIA, can determine the requirements for tribal citizenship.

“The Cherokee people have fought for centuries to preserve our rights of self-governance, through forced relocation, genocide and outright land theft,” Miller said.

Miller said the March vote was not racial in nature.

“We proudly count African-American Cherokees among our citizens,” he said.