Heath Ledger's death was accidental, resulting from misuse of a cocktail of painkillers, anxiety medication and sleeping pills, the New York coroner has found.

In a statement issued today, the city's medical examiner said: "Mr Heath Ledger died as the result of acute intoxication by the combined effects of oxycodone, hydrocodone, diazepam, temazepam, alprazolam, and doxylamine."

The medical examiner ruled out suicide.

"We have concluded that the manner of death is accident, resulting from the abuse of prescription medications."

While the medical examiner said his finding was accidental death, the statement did not elaborate on "the abuse of prescription medications".

There was no further comment in the brief formal statment.

Ledger's US-based publicist, Mara Buxbaum, immediately released a statement from Ledger's father, Kim, requesting the media to stop speculating about what killed his son.

"Today's results put an end to speculation, but our son's beautiful spirit and enduring memory will forever remain in our hearts," Mr Ledger wrote.

"While no medications were taken in excess, we learned today the combination of doctor-prescribed drugs proved lethal for our boy.

"Heath's accidental death serves as a caution to the hidden dangers of combining prescription medication, even at low dosage."

Ledger, the star of 2006 best picture Oscar nominee Brokeback Mountain and this year's Batman sequel, The Dark Knight, went public with his sleeping troubles in an interview with The New York Times late last year.

He complained he could sleep only two hours a night and his "body was exhausted".

Ledger told the newspaper two Ambien sleeping pills would give him just one hour of sleep.

Ellen Borakove, director of public affairs at the New York Chief Medical Examiner's Office, declined to say how many pills Ledger had taken to cause his death, nor the concentrations of each drug found in his blood.

Ledger's father's reference to "low dosage" however, and the ruling that Ledger died from an accidental overdose rather than suicide indicate large quantities of any one drug were not found in his bloodstream.

"It was the cumulative effects of these medications together," Ms Borakove said.