Baseball superstar Barry Bonds, the all-time Major League home-run king, pleaded not guilty to five counts of lying under oath about alleged steroid use.

Bonds, 43, entered the plea in his first appearance in a federal court in San Francisco since he was indicted last month on the perjury charges.

Federal prosecutors allege Bonds was untruthful when he told a grand jury in 2003 that he had taken substances given to him by his personnel trainer, but that he believed it was flaxseed oil - not steroids.

Bonds' attorneys have maintained all along their client is innocent and the victim of a witch-hunt. "We're confident of a good outcome," one of his lawyers said outside the courtroom.

The charges against Bonds arose during an investigation of Balco Laboratories, the San Francisco Bay area lab that was shut down for illegally distributing steroids to athletes. Several athletes have testified and at least one other got into trouble in the process.

US track superstar and Olympic gold medalist Marion Jones pleaded guilty this year to lying to federal investigators over her steroid use in connection to the Balco case.

Playing most of his long career for the San Francisco Giants, Bonds broke the all-time career home-run record last season, shattering the 755 mark set by Hank Aaron in 1976. Bonds finished the season with 762 career home runs.

The Giants announced in September that they would not sign Bonds for another season, making him a free agent. Bonds has been plagued with knee injuries and other physical problems in recent years, cutting sharply into his playing time and eroding his once stellar all-around skills.

Bonds debuted in Major League Baseball with the Pittsburgh Pirates in 1986 before joining the Giants in 1993.

Steroid use has clouded Bonds' pursuit of Aaron's record over the last several years and blemished one of America's most cherished sports milestones.