OKLAHOMA CITY (AP) - Descendants of former black slaves once owned by members of the Cherokee Nation have asked a federal judge to block a tribal election for principal chief until the tribe restores their full citizenship rights, including the right to vote.

Descendants of Cherokee freedmen have asked a federal judge in Washington, D.C., to enjoin a Sept. 24 election for principal chief of the Oklahoma-based tribe. A hearing on the request is set for Sept. 20.

Legal papers filed on Friday allege that the tribe is denying citizenship rights to the freedmen. The request for an injunction follows a recent Cherokee Supreme Court decision that terminated the freedmen's tribal citizenship.

The election was scheduled after the tribe's Supreme Court in July threw out the results of a disputed election for tribal chief.