Yakult Swallows right-hander Daniel Rios has tested positive for a banned substance, Japanese baseball sources said Saturday.
Rios, 35, is the third player to fail a doping test since Nippon Professional Baseball introduced a full-fledged anti-doping program last year.
Last August, Softbank Hawks right-hander Rick Guttormson was suspended for 20 days for the use of finasteride, which was contained in the hair-growing agent he had been taking for about two years.
Yomiuri Giants infielder Luis Gonzalez was slapped with a one-year suspension in late May after NPB's drug test found that he had taken stimulants clobenzorex, amphetamine and parahydroxyamfetamine.
Gonzalez was later released by Yomiuri.
Rios joined Yakult this year after notching double-digit wins for six consecutive seasons in South Korea. He went 2-7 with a 5.46 earned run average with the Swallows before being removed from the top-team roster on June 2.