RALEIGH, N.C. (AP) - Federal judges say nine North Carolina legislative districts redrawn by Republicans over the summer still may be unlawful.

A three-judge panel wrote Thursday it was concerned nine state House and Senate districts still fail to fix constitutional violations related to racial bias or "are otherwise legally unacceptable."

The judges want a Stanford University law professor with previous experience as a special master to evaluate those districts and possibly redraw them.

Voters who originally sued over boundaries approved by the GOP-controlled legislature in 2011 argued this month that 12 new districts remained illegal. Lawyers for legislative leaders disagreed and wanted the judges to sign off on new maps for the 2018 elections.