Osasuna have reported Barcelona to the RFEF for fielding an ineligible lineup in Tuesday's Copa de la Reina meeting.
Barça won the game 9-0 but face being thrown out of the competition after fielding Brazilian striker Geyse.
After being sent off in her last game in the Copa, while playing for Madrid CFF last season, Geyse was due to serve a suspension in Barça's first game in the tournament in the current campaign.
Barça say the ban did not show on the RFEF website or the internal system they use to check such issues.