SAN FRANCISCO, California (AFP) – In a last-minute twist in the Barry Bonds trial, prosecutors announced they had a recording of Bonds' surgeon discussing Bonds and steroids with the slugger's ex-business manager.

Doctor Arthur Ting threw a wrench in the prosecution's case last week when he denied ever having conversations about Bonds' alleged steroids use, contradicting testimony from a key government witness.

That witness, ex-business manager Steve Hoskins, told jurors he'd had "probably 50" conversations with the surgeon about Bonds' use of banned drugs.

Hoskins also said Ting researched specific steroids for Bonds and told Hoskins a 1999 elbow injury sustained by Bonds could only have been caused by steroids.

But when Ting got on the stand, he calmly denied all of it. "Did I have any conversations with Stevie about steroids?

"With confidence, I can say I didn't discuss that," he said.

In prior testimony, Hoskins said he had attempted to secretly record one such discussion but later wasn't able to find the tape and wasn't sure if it had recorded properly.

After Ting denied the discussions took place in court last week, Hoskins apparently found the tape.

Bonds, the US home run king, is on trial on charges of perjury and obstruction of justice in connection with testimony he gave in 2003 to a grand jury investigating steroids.

In that testimony, he acknowledged taking substances he believed were flaxseed oil and arthritis balm but denied knowingly using performance-enhancing drugs.

The discovery of the tape is a remarkable turn of events in a case that was expected to wrap up as soon as tomorrow.

Instead, the jury was dismissed for the day after one juror reported sick, and court proceedings turned to how to handle the new evidence.

Prosecutor Matthew Parrella told US District Judge Susan Illston they received the microcassette, the kind used in answering machines, from Hoskins late Sunday night.

The tape contains a roughly 15-minute conversation between Hoskins and Ting about Bonds and steroids that took place at Ting's Northern California medical practice "soon after the BALCO search warrants were executed," Parrella said.

BALCO is the Bay Area Laboratory Co-operative, the strip-mall steroids mill that distributed then-undetectable drugs to professional athletes. Bonds? trainer?s house was raided the same day.

In his testimony almost two weeks ago, Hoskins said he repeatedly spoke with Ting about Bonds? steroid use. On one occasion, "Barry was sore and I wanted to know if he could keep shooting ... in the same place," he said.

At one point, Ting advised him that the steroids "were not good and to tell Barry to stop taking them."

In his testimony, Ting acknowledged giving Hoskins some printouts on steroids, which prosecutors had already introduced as evidence.

But he denied that Hoskins had told him the information was for Bonds, or that he ever researched specific drugs for the Giants star.

In addition to contradicting a key government witness, Ting's testimony undercut an anti-doping expert who had told jurors about the side effects of anabolic steroids.

Ting said Bonds' alleged symptoms - bloating, acne, sexual dysfunction - could also have been caused by legal corticosteroids commonly taken for inflammation.

Parrella told Judge Illston on Monday that his office was working on preparing a transcript of the tape. Defence lawyers said they would need to have their own expert authenticate the recording. Judge Illston did not immediately rule whether prosecutors will be allowed to play the tape for jurors.

If the tape is admitted as evidence, the government will likely ask the judge for permission to call Hoskins back to the witness stand this week.