Ledger's death accidental 

Actor Heath Ledger died of an accidental overdose of prescription drugs, including painkillers, tranquillisers and sleeping aids, officials said.

"We have concluded that the manner of death is accident, resulting from the abuse of prescription medications," the New York City Medical Examiner's Office said in a statement.

Australian-born Ledger, 28, renowned for his role as a conflicted gay cowboy in the 2005 movie Brokeback Mountain, was found dead in his Manhattan apartment on January 22, naked and with several prescription drugs nearby.

His death shocked film fans and fellow actors around the world and added his name to the list of movie stars who died young like Marilyn Monroe and James Dean.

An autopsy the day after his death proved inconclusive pending tissue and toxicology tests, the results of which results were released on Wednesday.

"Mr Heath Ledger died as the result of acute intoxication by the combined effects of oxycodone, hydrocodone, diazepam, temazepam, alprazolam, and doxylamine," the statement said.

Oxycodone, which is often abused, and hydrocodone are painkillers. Diazepam and alprazolam are anti-anxiety medicines. Diazepam is sold under the brand name Valium and alprazolam is sold under the name Xanax.

Temazepam is a sleep aid sold under the name Restoril. Doxylamine, a sleep aid and antihistamine, is an active ingredient in a number of over-the-counter medications, including NyQuil.

In a statement on behalf of the family, his father, Kim Ledger, thanked the actor's fans for their outpouring of support and asked to be allowed to grieve privately.

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

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

The handsome star had been romantically linked with a number of actresses and models, periodically spotted in fancy clubs and night spots around New York.

He recently had been in a committed relationship with actress Michelle Williams, the mother of their 2-year-old daughter, Matilda, but the couple split in September. Some reports said Ledger was having difficulty with the breakup.

The couple met during the filming of Brokeback Mountain, in which they played husband and wife.

Ledger received an Oscar nomination for Brokeback Mountain and had completed filming his role as The Joker in The Dark Knight, a Batman film due out this year.

Other film credits included The Patriot in 2000, Monster's Ball in 2001 and I'm Not There in 2007.