Veteran Seattle Sounders defender Roman Torres has been suspended 10 games by Major League Soccer for testing positive for a performance-enhancing substance.

The test result violated the league's Substance Abuse and Behavioural Health Policy and also carries with it a fine of 20 per cent of his annual salary.

During his suspension, Torres is barred from any and all team activities, but Torres is permitted to train with the club's USL affiliate, the Tacoma Defiance, two weeks prior to his return date.

The 33-year-old Panama international is eligible to return on September 29 when the Sounders visit the San Jose Earthquakes.

Torres is in his fifth season with the Sounders. He scored the winning goal in the team's shootout victory over Toronto FC in the 2017 MLS Cup Final.