SAN DIEGO – Mike Cameron, the Padres’ Gold Glove center fielder, was suspended for the first 25 games of next season on Wednesday after testing positive a second time for a banned stimulant.

Cameron, who plans to file for free agency, said he believes he took a tainted supplement.

“The one thing I wanted to make sure was explained is, no steroids,” Cameron told AM 1090, the Padres’ flagship radio station. “I never took nothing like that before in my life. That would be 50 games, and that would affect me a whole lot more.”

Cameron issued a statement through his agent, saying doctors for the players’ association helped him narrow down what triggered the positive test.

“After all of the analysis and testing, I can only conclude that a nutritional supplement I was taking was tainted,” he said. “Unfortunately, the actual supplement is gone, and therefore cannot be tested. Without the actual supplement in hand, the rules are clear, and I must accept the suspension.”

Players who initially test positive for a stimulant receive counseling. Suspensions begin only with a second positive test.

“Mike has been a valuable member of the Padres over the last two seasons who has been respected for his contributions on the field, his stature in the clubhouse and his involvement in the San Diego community,” Padres CEO Sandy Alderson said in a statement. “Accordingly, the Padres are extremely disappointed that Mike has tested positive for a stimulant banned by MLB’s drug policy. Nonetheless, the Padres staunchly support that policy and hope that Mike’s suspension serves as a reminder that performance-enhancing drugs have no place in professional sports.”

Cameron missed almost the entire final week of the season after fellow outfielder Milton Bradley inadvertently stepped on his right hand while the two pursued an inside-the-park home run by Colorado’s Garrett Atkins on Sept. 23. Cameron made a pinch-running appearance in San Diego’s 13-inning loss at Colorado on Oct. 1 in the wild-card tiebreaker game.

In his second season with the Padres, Cameron’s offensive numbers fell off this season, as he hit just .242 and struck out 160 times. He hit 21 homers.

Cameron is best-known for hitting four home runs in a game in 2002 and for a frightening collision in Petco Park’s outfield three seasons later.

The only other player suspended for testing positive for stimulants under Major League Baseball’s drug plan was Detroit infielder Neifi Perez, who received a 25-game suspension on July 6 following his second positive test, and an 80-game suspension on Aug. 3 following his third positive test.