Baseball commissioner Bud Selig (search) expressed concern Saturday about fresh allegations that Barry Bonds (search) used performance-enhancing drugs in 2003 and said they are further cause for a tougher policy on steroid use to avoid tarnishing the game.

Selig told reporters at the American League championship series game in Boston that a San Francisco Chronicle story based on a tape recording purportedly of Bonds' trainer is "just a further manifestation of why we need a very strict steroid policy. Until we have one, we'll have this kind of situation."

The Chronicle obtained from an anonymous source a 9-minute recording it said was of Bonds trainer Greg Anderson, one of four people charged in a steroid scandal involving a Bay area nutritional supplements firm.

The speaker on the tape is heard saying Bonds used an "undetectable" performance-enhancing drug during the 2003 season and boasting that he would be tipped off up to two weeks before random drug testing, the newspaper said. Bonds has denied taking steroids.

"I'm concerned," Selig said, cautioning that "these are merely allegations. I'm not ready to pass judgment."

But he said the issue is detracting from the game.

"Here we are in Game 3 of the Red Sox-Yankees — people have waited for this all year — Cardinals and Houston, and what are we sitting here and talking about?" Selig said. "This is not good for the sport. This is not good for any of the parties involved, and, of course, I include the fans."

The Chronicle quoted Anderson as saying he was confident Bonds could pass a drug test, not just because the drugs could be masked but because he would be warned in advance.

"I'll know like probably a week in advance or two weeks in advance before they're going to do it," Anderson was recorded as saying, according to the Chronicle.

The league banned the use of steroids beginning with the 2003 season. The tape recording was made in the spring of that year, the Chronicle said.

Rob Manfred, a Major League Baseball executive vice president who is the commissioner's point man on the steroids policy, disputed Anderson's claim.

"With respect to advance notice, given the procedures that were in place, there is no way that Greg Anderson or Barry Bonds had advance notice of when he was going to be tested," Manfred told the newspaper. "I didn't know when he was going to be tested."

Anderson, 38, a longtime friend of Bonds, also said on the recording that he had experience using and dispensing performance-enhancing drugs that could escape detection, according to the report. He said the drug he was giving to Bonds also was given to Olympic athletes.

"The whole thing is, everything that I've been doing at this point, it's all undetectable," Anderson is quoted as saying. "See the stuff I have, we created it, and you can't buy it anywhere else, can't get it anywhere else, but you can take it the day of (the test), pee, and it comes up perfect."

The Chronicle said two people who know Anderson listened separately to parts of the recording and identified the voice as his.

Anderson's lawyer, J. Tony Serra, listened to portions of the tape and said he was unable to identify the person speaking, the paper said.

Serra said his client "categorically denies" providing banned substances to Bonds and called the recording a "red herring" that doesn't prove otherwise.

Bonds' attorney, Michael Rains, said the newspaper's report was "the product of what has to be an illegally recorded telephone conversation supposedly between Greg Anderson and an anonymous criminal."

He called the tape recording and subsequent story "simply another below-the-belt bash of Barry Bonds."

Bonds has insisted that he has never used steroids. Last month, he told MLB.com, the Web site of Major League Baseball, that he had been randomly selected to submit to steroid testing this year and that he welcomed the chance to prove his achievements were accomplished naturally.

The Chronicle report says that many of the trainer's comments on the tape make it clear Bonds is the subject of the conversation. The voice describes the six-time Most Valuable Player's unique batting achievements in specific detail, including his record 73 home runs in 2001.