Yomiuri Giants infielder Luis Gonzalez filed an appeal Tuesday against the one-year suspension handed down to him the previous day by Nippon Professional Baseball for doping violations.

NPB's drug test conducted in late April found that Gonzalez had taken stimulants clobenzorex, amphetamine and parahydroxyamfetamine, which are on the list of banned substances in Japanese baseball.

Gonzalez has a period until June 10 to make explanations to the NPB anti-doping special committee, but Kazuo Hasegawa, executive director of the baseball commissioner's office, said, "We have received documents from Gonzalez, but there is no evidence to back up his claim."