Ledger, 28, was found after a possible drug-related death in his central Manhattan apartment on Tuesday, New York police department spokesman Paul Browne said.

The Australian-born actor's body was discovered by his housekeeper at around 3.30pm local time after she went to let him know a masseuse had arrived for an appointment, Mr Browne said.

Police said they did not suspect foul play and Ellen Borakove, a spokeswoman for the city's medical examiner's office, said an autopsy was planned for Wednesday.

Mara Buxbaum, Ledger's publicist, said: "We are all deeply saddened and shocked by this accident."

At the scene, a police spokesman said Ledger was found naked at the foot of the bed, face down.

Prescription drugs, including sleeping pills, were found nearby and there was no evidence that a party had taken place. No suicide note was found, the spokesman said.

In Australia, Ledger's father Kim spoke of his family's grief and said the actor's death was accidental.

"We, Heath's family can confirm the very tragic, untimely and accidental passing of our dearly loved son, brother and doting father of Matilda," Mr Ledger said in Perth.

"He was a down-to-earth, generous, kind-hearted, life-loving unselfish individual extremely inspirational to many."