Michael Jackson [File photo]

Michael Jackson's former doctors have been banned from testifying at the trial of Dr. Conrad Murray.

The defence team for the 'Thriller' hitmaker's personal physician - who denies the involuntary manslaughter of the singer - were dealt a huge blow by Los Angeles Superior Court Judge Michael Pastor, who has banned six medical professionals who had treated the star from appearing at the trial.

These include Dr. Arnold Klein, who had been dermatologist and friend to Michael for a long time before his death from acute Propofol intoxication in June 2009.

The defence lawyers are thought to have been hoping to use the testimony of the medical professionals to show the 'Billie Jean' hitmaker was addicted to strong painkilling drugs before he started receiving treatment from Dr. Murray.

In court papers filed at a pre-trial hearing yesterday (29.08.11), defence attorneys Edward Chernoff and Nareg Gourjian alleged Dr. Klein had "administered frequent intramuscular injections of Demerol to Mr. Jackson for no valid medical purpose," and that the star had "became physiologically and psychologically dependent on Demerol."

The prosecution argued this defence was trying to divert attention from Dr. Murray and allege Dr. Klein was in some way a factor in Michael's death.

Judge Pastor said he didn't feel the defence's claims were "relevant" and would be distracting and misleading for the jury.

However, the judge did approve testimony from doctors Allen Metzger - who reportedly refused to give the singer an intravenous sedative when he requested it - and David Adams, who gave him Propofol on four occasions in 2008, after the singer had oral surgery.

Dr. Murray faces up to four years in prison.

Jury selection for the trial will begin on September 8, and opening statements are scheduled to begin at the trial on September 27.