The star, who made her breakthrough in 1995 teen comedy Clueless opposite Alicia

Silverstone, was found unconscious in the shower yesterday morning by her mother.

Assistant Chief Coroner Ed Winter confirmed this and said that the death "appears to be natural," although further tests will be carried out. There will also be a probe into the star's medical history.

When paramedics arrived they realised Murphy was in full cardiac arrest and immediately tried to resuscitate her.

The actress was taken to Cedars-Sinai Medical Centre but pronounced dead on arrival by hospital staff.

Los Angeles Fire Department spokesman Devon Gale said crews responded to a call from a home in Los Angeles that is listed as belonging to Murphy’s husband, British screenwriter Simon Monjack.

In November he was reportedly taken to hospital in Los Angeles following a flight from Puerto Rico to California. He was said to be incoherent when help arrived on board.

Murphy, who starred in hits such as Girl, Interrupted, 8 Mile and Sin City, was reportedly fired from her last film, The Caller, after reports she was problematic on set. The thriller was being filmed in Puerto Rico.

Last year it was announced that she had been replaced as the voice of Tinker Bell, the

mischievous fairy from JM Barrie’s Peter Pan, in a series of animated films directed by John Lasseter.

Born in 1977, in Atlanta, Georgia, Murphy grew up in New Jersey and later moved with her mother to Los Angeles to pursue acting.

Her career started in the early 1990s with small roles in commercials and television series such as Blossom, Party of Five and Sister, Sister.

Her on-screen roles declined in recent years, but Murphy’s voice gave life to numerous animated characters, including Luanne Platter on more than 200 episodes of Fox’s King of the Hill, for which she won an Annie animated film award in 2005.

She also provided the voice of Gloria the penguin in the animated hit Happy Feet.

She is due to appear in Sylvester Stallone’s upcoming film The Expendables, an action thriller about a team of mercenaries, which is scheduled for release next year.

Her role as rapper Eminem’s girlfriend in the film 8 Mile led to more recognition. In 2003 the actress said of the role: "That changed a lot. That was the difference between people knowing my first and last name as opposed to not."

Murphy credited the support of her mother, Sharon, as key to her success. "When I asked my mom to move to California, she sold everything and moved out here for me," she said.

"I was really grateful to have grown up in an environment that was conducive to creating and didn’t stifle any of that. She always believed in me."

The actress was the subject of speculation earlier this year when in an appearance on US talk show The Late Late Show with Craig Ferguson she behaved in an eccentric manner and spoke with an Irish accent.

Murphy dated Ashton Kutcher, with whom she co-starred in 2003’s romantic comedy Just Married. On his Twitter site Kutcher wrote: "2day the world lost a little piece of sunshine. My deepest condolences go out 2 Brittany’s family, her husband, & her amazing mother Sharon".