U.S. District Judge Susan Illston on Friday threw out evidence in the perjury trial of former San Francisco Giants slugger Barry Bonds.

Among the evidence tossed was statements allegedly made by Bonds former trainer linking him to positive tests for performance-enhancing drugs.

Illston said documents concerning tests done on Bonds' urine by Quest Diagnostics Inc. cannot be used by prosecutors without verification from trainer Greg Anderson, who refuses to testify.

The ruling is the latest setback for prosecutors as they prepare their case against Bonds.

On Wednesday, Illston ruled that potential jurors cannot be asked whether they have heard about steroid use by New York Yankees third baseman Alex Rodriguez.

Bonds faces 10 counts of perjury for allegedly lying to a grand jury about taking steroids, and one count of obstruction of justice.

Bonds contends that he was under the impression that the substances Anderson gave him were legal herbal supplements.

Bonds' trial is scheduled to begin on March 2 and is expected to last about a month.