Barry Bond's former personal trainer was jailed today for refusing to testify before a grand jury reportedly investigating whether the US baseball slugger lied about steroid use.

Greg Anderson was taken into custody by US marshals a federal judge declared him in contempt of court for defying an order to answer questions before a grand jury in San Francisco.

Anderson was to remain in jail until he agreed to capitulate.

Anderson had served three months behind bars as part of a plea bargain stemming from his role in the Bay Area Laboratory Cooperative (BALCO) steroid scandal that shook the sporting world.

Anderson's lawyer, Mark Geragos, stepped from the courthouse and condemned the judge's decision.

Anderson was being unfairly punished because his plea deal in the BALCO case did not require him to help with any investigation into steroid use by professional athletes, Geragos said.

"In his mind and a lot of other people's minds this is nothing more than piling on," Geragos told reporters outside the courthouse.

"He negotiated a plea deal that did not involve cooperation."

Geragos said he would appeal the judge's contempt ruling.

BALCO fallout has tainted elite athletes such as Olympic sprinters Tim Montgomery and Marion Jones and baseball stars Jason Giambi and Bonds.

Anderson's was one of a string of guilty pleas arising from the production and supply of virtually undetectable steroids to top athletes by BALCO from June of 2000 through 2003. In the wake of those convictions, prosecutors are seeking to indict San Francisco baseball hero Bonds on charges he lied under oath to the federal grand jury during the BALCO probe.

Bonds, whose major league batting record is second only to that of Hank Aaron, has been hounded after saying he used a balm and clear liquid prosecutors say were illegal performance-enhancing drugs made by BALCO.

Bonds has denied knowingly taking steroids even though Anderson was his close friend and personal trainer when BALCO was channeling performance enhancing drugs to athletes.

The BALCO scandal sparked tougher drug testing in US sports, although far from the level used by the World Anti-Doping Agency.

AFP