SAN FRANCISCO - A federal grand jury is investigating whether Barry Bonds committed perjury when he testified in 2003 that he never used steroids, a person with knowledge of the probe told The Associated Press on Thursday night.

The person spoke on condition of anonymity because of the secrecy of the investigation.

The panel has been hearing evidence for more than a month about whether Bonds lied to a different grand jury that was investigating the BALCO scandal. The existence of the grand jury was first reported by CNN on Thursday.

Luke Macaulay, spokesman for the U.S. Attorney's Office in San Francisco, told the AP that he could neither confirm nor deny the reports.

Bonds was granted immunity when he testified before the BALCO grand jury in December 2003, as long as he told the truth. According to excerpts of the testimony previously reported by the San Francisco Chronicle, Bonds testified that he used a clear substance and a cream given to him by a trainer who later pleaded guilty in a steroid-distribution ring, but said he didn't know they were steroids.

Bonds told the grand jury that Greg Anderson, his personal trainer, told him the substances he used were the nutritional supplement flaxseed oil and a rubbing balm for arthritis.

The substances Bonds described were similar to ones known as "the clear" and "the cream," two steroids at the center of the Bay Area Laboratory Co-Operative scandal. Investigators seized calendars that recorded schedules for Bonds' use of those drugs, as well as human growth hormone, clomid, insulin and other steroids, according to the Chronicle.

Bonds, who has always denied using steroids, left the     San Francisco Giants ballpark Thursday night without answering questions about the report from reporters. When asked what he would tell his fans, Bonds responded, "Tell them I love them."

Following last month's release of the book "Game of Shadows," which details steroid use by Bonds and other players, baseball commissioner Bud Selig launched an investigation of steroids in baseball.

Harry Stern, an attorney in the firm representing Bonds, told the AP that Bonds told the truth when he testified to the grand jury and said his firm had no knowledge of the new grand jury investigation.

Baseball spokesman Rich Levin said he is aware of the reports, "but it's just not appropriate for us to comment at this time."

Dr. Arthur Ting, Bonds' personal surgeon, has been subpoenaed to testify before the grand jury investigating possible perjury charges, the source told the AP. Ting, who treated Bonds for a knee injury that kept him out for most of the 2005 season, will be called to appear before the panel meeting at U.S. District Court in San Francisco, the source said.

Phone messages left by the AP for Ting were not immediately returned Thursday night.

According to "Game of Shadows," Ting accompanied Bonds to BALCO headquarters in Burlingame in 2003 to draw blood from the slugger.

Bonds is third on baseball's all-time home runs list with 708; he is seven homers shy of passing Babe Ruth, but has not homered in the Giants' first eight games this season.

Bonds was one of about 30 athletes who testified to the grand jury investigating BALCO, including     New York Yankees sluggers Jason Giambi and Gary Sheffield, and track stars     Tim Montgomery and     Marion Jones.

None of the athletes had to testify in open court because the four defendants pleaded guilty last year to the charges. Anderson was sentenced to three months in prison and three months in home confinement; BALCO founder Victor Conte was sentenced to four months in prison and four months home confinement; and BALCO vice president James Valente and track coach Remi Korchemny each received probation.