NEW YORK — The World Boxing Council has opened an investigation of Shane Mosley following recent reports that the fighter testified under oath to taking performance-enhancing drugs in the lead-up to his 2003 title bout against Oscar De La Hoya, the New York Daily News reported Tuesday.

Nearly three months after winning the WBC junior middleweight title with his victory over De La Hoya, Mosley told a grand jury he used steroids and EPO as part of his training regimen for the fight.

Mosley insists he didn't know the drugs he took were banned or illegal.

"It was a real surprise to read that Mosley has confessed that he did take those medicines, those drugs that are totally prohibited by the WBC," said the council's president, Jose Sulaiman. "The WBC rules state that we must have a hearing. This is a matter of serious concern to us."

Sulaiman has ordered the WBC's legal counsel to gather evidence on Mosley to present to the Council's 29-member board of governors. The board has the authority to vote on sanctions and can issue disqualifications or severe fines, even after the conclusion of a fight.

"Thus far the WBC has seen only press reports, and must therefore investigate any available evidence and review it, in terms of the WBC rules and regulations' anti-doping provisions," said Robert Lenhardt, an attorney for the WBC.

The investigation will coincide with a defamation lawsuit Mosley filed against BALCO founder Victor Conte. The suit claims Conte told newspapers he watched Mosley inject himself with EPO and that the boxer knew what he was taking.

Conte, who is in possession of the grand jury transcripts because he was a defendant in the BALCO case, said he is "more than willing to cooperate with any investigation of Shane Mosley's use of performance-enhancing drugs."

The WBC rules include a prohibition that no boxer "shall be under the influence of any drug during the contest that will in any manner affect their performance in the ring."

Mosley, a four-time world champion, is scheduled to meet current WBA welterweight title holder Antonio Margarito on Jan. 24 at Staples Center in Los Angeles.