BURLINGAME, Calif. -- A federal grand jury in San Francisco is investigating a Burlingame nutritional supplement company that boasts of its ties to star athletes.

The Bay Area Laboratory Co-Operative, or BALCO, is the object of an investigation led by the Internal Revenue Service, according to a Tuesday report from The San Francisco Chronicle.

The newspaper reports that the IRS is being assisted by the Food and Drug Administration, the San Mateo County Narcotics Task Force and Olympics drug-testing officials.

The company's offices were raided on September 3rd. Two days later, agents searched the home of Greg Anderson, one of Barry Bonds' personal trainers. Bonds is the company's most noted endorser, though he's not the only athlete whose name it advertises.

Anderson, once a regular in the Giants' clubhouse, was last seen around the team a few days before the early-September raids, the Chronicle reported. BALCO owner Victor Conte has said that he serves as Bonds' nutritionist and that Anderson is the Giants star's weight trainer.

Bonds' agent, Scott Boras, said last week that the BALCO case "really doesn't involve'' Bonds and that he had no knowledge of any request for the outfielder to testify before a grand jury.

BALCO claims that it helps athletes by determining mineral and trace element deficiencies through blood and urine analysis and then providing them with various supplements.

According to Conte and company Web sites, the client lists of BALCO and its supplement wing Scientific Nutrition for Advanced Conditioning (SNAC) include several Olympic athletes past and present, tennis stars, body builders and professional football players. But there is only one baseball star -- Bonds.

The 39-year-old slugger's picture adorns the company Web site, biceps glistening from the page, a hat bearing the name of the business' signature product atop his head.

Bonds has worked with BALCO since the winter of 2000. Since he began his association with Conte, Bonds, who also follows a rigorous exercise and weight-training program, has produced a staggering three-season stretch: .345 batting average, 164 home runs -- including the single-season record of 73 in 2001 -- and 337 RBI.

Not all the athletes listed as BALCO clients recalled an association with the firm.

In an interview published in the September 1999 issue of Muscular Development magazine, Conte said BALCO had "provided testing and consultation for over 250 NFL players, including the entire Denver Broncos Super Bowl championship team, as well the entire Miami Dolphins team."

A Broncos spokesman told the Chronicle that the team was never a client of BALCO's and that any players who used the company did so on their own. Dolphins strength and conditioning coach John Gamble said that in 1998 Conte tested all of the Dolphins players for mineral deficiencies and that he subsequently sent supplements to counteract those deficiencies. Gamble said, though, that he did not believe Conte was paid for his services.

Former Olympic hurdler and wide receiver Renaldo Nehemiah said he was sent to BALCO by the San Francisco 49ers in the early 1980s for testing because he was lethargic and it was thought he had some sort of nutritional deficiency.

Nehemiah told the Chronicle that Conte had contacted him, and the two talked about foods the wideout should avoid.

"That's my involvement," said Nehemiah. "Unfortunately for Victor, he can't take credit for working with me in any supplemental capacity.'' The former NFL player said he has never taken supplements.

Lance Deal, a four-time Olympian and 1996 Olympic silver medalist in the hammer throw, said that BALCO's listing him as a client is a "gross exaggeration.'' Deal, now coaching at the University of Oregon, told the paper that he had a brief association with BALCO in the mid-1980s, when the company did some testing of U.S. hammer throwers.

Deal did say, though, that the business seemed legitimate at the time, that he and others had their blood tested and that supplements were then suggested. He couldn't recall acting on the recommendations.

Conte told the Chronicle that he has neither been told that he is a target of the grand jury investigation nor has been asked to testify before the panel. The agencies have not indicated what they're looking into.

The IRS said it cannot comment on the investigation because it is ongoing, and the FDA referred calls to the IRS as the lead agency. But one source, who spoke to the Chronicle on condition of anonymity, said he has been subpoenaed to testify in November before the grand jury in San Francisco, and a second source said he was contacted by another person subpoenaed to testify later in October. All documents relating to the investigation are sealed, and none of the agencies has commented publicly other than to acknowledge the searches.

The Chronicle further reported that the source called to testify as a witness next month said he was told by agents of the U.S. Department of Treasury -- which oversees the IRS -- that the investigation centered around BALCO and Anderson.

Information from The Associated Press was used in this report.