SAN FRANCISCO (AP) – A federal grand jury is investigating whether Barry Bonds committed perjury when he testified in 2003 that he never used steroids, according to media reports.

The panel has been hearing evidence for more than a month about whether the Giants’ slugger lied to a different grand jury that was investigating the BALCO scandal, according to reports Thursday night on CNN and the San Francisco Chronicle’s Web site.

Luke Macaulay, spokesman for the U.S. Attorney’s Office in San Francisco, told The Associated Press that he could neither confirm nor deny the reports. The story was first broadcast on CNN, which cited “multiple sources” it did not identify.

Harry Stern, an attorney in the firm representing Bonds, told the AP that “We don’t have any knowledge about” a grand jury investigation. He also said he stands by previous statements that his client did not perjure himself during his 2003 testimony. Baseball spokesman Rich Levin said he is aware of the reports, “but it’s just not appropriate for us to comment at this time.”

The Chronicle also reported that Dr. Arthur Ting, Bonds’ personal surgeon, has been subpoenaed to testify before the grand jury investigating possible perjury charges.

Ting, who treated Bonds for a knee injury that kept him out for most of the 2005 season, was called to appear before the panel at the U.S. District courthouse in San Francisco later this month, the Chronicle reported, citing two people familiar with the investigation.

The sources asked the newspaper not to identify them because of the sensitivity of the grand jury probe.

Bonds has repeatedly denied ever using steroids, including during his testimony to the grand jury investigating BALCO. The Chronicle’s sources told the newspaper that federal investigators believed Bonds was lying because documents seized in government raids included documentation of the slugger’s drug use.

Last month’s publication of the book “Game of Shadows,” which detailed Bonds’ alleged drug regimen, prompted Major League Baseball commissioner Bud Selig to launch an investigation into past steroid use in baseball.

Bonds is third on baseball’s all-time home runs list with 708; he is seven homers shy of passing Babe Ruth. He did not play in the second game of Thursday’s doubleheader with the Houston Astros in San Francisco and was not made available for comment.

AP-ES-04-13-06 2216EDT