The 27-year-old was a regular for the Whites during the 2020-21 season, contributing five goals and five assists in 27 appearances in all competitions.
The Angolan international still has three years remaining to run on his contract at Elland Road, but there is currently speculation surrounding his future.
Marcelo Bielsa’s side are thought to be in the market for a new right-sided attacker.
According to The Athletic, Los Ches are one of a number of Spanish clubs keeping a close eye on Costa’s situation with the Yorkshire giants.
The report adds that the La Liga outfit are yet to make a formal offer but have registered their interest during the current transfer window.
Costa joined Leeds on loan in 2019 but made a permanent switch in 2020 from Wolverhampton Wanderers.