Heath LedgerHeath LedgerA private memorial was held for Heath Ledger in Los Angeles this weekend.

Michelle Williams and Naomi Watts were among those who mourned the star.

Heath's sudden death last week left the celebrity world, and especially those who knew him, shocked and distraught.

On Saturday, friends and family of the 28-year-old actor gathered in the Beverly Hills Hotel, Los Angeles for a private 30-minute ceremony to mourn his passing.

Heath's ex-fiancee Michelle, with whom he had a two-year-old daughter Matilda, as well as his former girlfriend and fellow Aussie Naomi, were among the guests.

Earlier in the day, around 1,000 people attending the USA Australia Day ball in New York shared their grief by listening to a message written by Heath's father, Kim.

"Heath did not become an actor for the fame or fortune. He loved his craft and he loved helping his friends.

"He loved chess and skateboarding too," said the letter from Kim, read to guests by the Australian consul-general.

"My image of Heath in New York is him with his skateboard, a canvas bag and his beanie. That was Heath to me."

Heath was found dead in his New York apartment on Tuesday.

The cause of his death has yet to be established, although a source close to the police investigation said that he may have died from natural causes, as the levels of toxins found in his system were so unusually low.

Heath's body is reportedly being flown back to his hometown of Perth today to be buried.