A judge has dismissed all but one count in a civil lawsuit by Michael Jackson's mother against concert giant AEG Live, which employed the doctor convicted of involuntary manslaughter in the singer's death.

Superior Court judge Yvette Palazuelos' ruling in Los Angeles means Katherine Jackson will have a trial on her claim that AEG negligently hired and supervised former cardiologist Conrad Murray.

But the ruling dismissed claims that AEG could be held liable for Murray's conduct and breached its duty to properly care for the pop superstar.

AEG Live was promoting a series of This Is It comeback concerts by Jackson in London. Jackson, 50, died in June 2009 while in final preparations for the shows after Murray administered a lethal dose of the anaesthetic propofol in the singer's bedroom.

Katherine Jackson's lawyer Kevin Boyle argued at a hearing on Monday that AEG controlled Murray's actions and failed to properly investigate him before agreeing to pay him to work as the singer's doctor.

He cited Murray's debt problems as a red flag that AEG should have spotted and said the company created a serious conflict between his responsibility to Jackson and his own financial well-being.

Jackson died before a contract that would have paid Murray 150,000 dollars (£100,000) a month was finalised.

AEG lawyer Marvin Putnam has said Murray was not employed by the promoter and he expects the company to win at trial.

He said Katherine Jackson's lawyers would be unable to prove that AEG should have foreseen that Murray was a danger to the Thriller singer.

The trial is due to begin on April 2.