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The insurers of Michael Jackson's ill-fated "This Is It" London comeback concerts have asked a judge to nullify a $17.5 million policy taken out by promoters, saying they were never told that the singer was taking powerful drugs.

Underwriters at Lloyds of London filed a lawsuit against AEG Live and Jackson's company in Los Angeles Superior Court on Monday, asking a judge to solve the insurance dispute almost two years after the "Thriller" singer's death.

Jackson, 50, died in Los Angeles on June 25 after rehearsing for the upcoming series of 50 concerts in London. Authorities said he died of a massive dose of the anesthetic propofol and a cocktail of other sedatives and painkillers.

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Jackson's personal doctor is scheduled to stand trial in September on charges of giving the singer a fatal dose of propofol as a sleep aid.

The insurance policy was taken out to cover the cancellation or postponement of the London concerts in the case of the death, accident or illness of Jackson.

The lawsuit claimed that AEG, who hired Jackson's physician Dr. Conrad Murray, failed to disclose the singer's medical history to the insurers "including, but not limited to, his apparent prescription drug use and/or drug addiction."

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The lawsuit further states that AEG or Jackson or his company knew but did not disclose that Jackson was taking propofol -- an anesthetic that is usually restricted to hospital use ahead of surgery.

It adds that attempts to resolve the dispute with AEG Live outside the courts have failed. "Underwriters therefore request that the policy be declared null and void."

AEG Live, which is privately held, did not return calls for comment on Tuesday.

(Reporting by Jill Serjeant, editing by Christine Kearney)