SAN FRANCISCO — A federal judge has ordered Barry Bonds' personal trainer, Greg Anderson, to court to disclose whether he intends to testify at the slugger's trial next month.

U.S. District Judge Susan Illston scheduled a hearing for Wednesday morning and ordered the U.S. Marshals Service to tell Anderson and provide him with transportation, if needed.

The judge has barred prosecutors from using key evidence, such as positive steroids tests, at Bonds' March 2 trial unless Anderson testifies.

Anderson has said through his attorney he will refuse to testify, and he may be sent to prison on contempt of court charges. Anderson was sent to prison after refusing to testify about Bonds before a federal grand jury in 2006.