Muriel's Wedding star Rachel Griffiths admits she's a real swot over voice coaching and her accent in Six Feet Under, the quirky US TV series about a family of undertakers, is so convincing her American audience didn't guess she's from Down Under.

Although she's made her name as a movie actress, Rachel Griffiths had no problem signing up for the US television series Six Feet Under. "I had a huge pile of movie screenplays and this incredible TV script," says the actress. "What's not to like that every two weeks I get one of the best scripts in the world and it has my name on the top."

Few would disagree. The series, a dark and quirky tale about a family of undertakers, is an adult American hit to rank alongside The Sopranos, The West Wing and Sex And The City.

Griffiths won a Golden Globe award for her performance as Brenda, a temperamental and dysfunctional American. Just don't ask where the award is. She'd mislaid it temporarily when we spoke in London a few weeks ago. "I'm not sure where it is," she admits. "I'm hoping it's being shipped from America to Australia, but I don't remember packing any boxes or seeing it in the house when I left."

No matter, more acclaim will surely come her way to add to the Oscar nomination received for Hillary And Jackie, and the two Australian awards won for Muriel's Wedding.

It's no wonder the Americans don't know what to make of her. Because of Six Feet Under, some don't even realise the Melbourne-born actress is from Down Under. There was a period when she might have been taken for a Yorkshirewoman after three films - Among Giants, My Son The Fanatic and Blow Dry - playing characters from that part of the country.

"I'm a real swot over accents," she says. "My worst fear is reading a review that says I have the worst-ever accent in a British, Irish or an American movie. So I just work really hard at it.

"I've had pretty much the same two British voice coaches on the movies I've done, and the more you work with a voice coach, the more they understand what your strengths are. I'd rather take half the money than work without a coach."

Americans were surprised when she accepted her Golden Globe in an Aussie accent. So were the crew on the set. "I had so little time to get the accent, I just stayed in it all the time," she says. "On the last day I dropped it and some of the crew just couldn't handle it. Someone asked me what I was going to do next and I said, 'I'm going back to Australia'. He dropped his coffee cup and went, 'you're kidding me, aren't you?'. It totally freaked him out."

For a movie called Very Mary Annie, she adopted a Welsh accent without attracting any adverse remarks in the press. It was touch and go whether she got it right. "Two days before filming I was doing that thing of speaking in the accent all the time. I tried it on a taxi driver and he said, 'you sound like a Swedish Rastafarian'. I rang up the voice coach and said that we must work harder."

Home will always be Australia, where she shares a beach house with fiance Andrew, whom she plans to marry next year. Filming Six Feet Under keeps her in the States six months of the year.

"Home is a kind of mental thing as well as where you keep your recipes and photograph collection. At the moment I'm probably not likely to be there that much.

"But life is bigger than one's career. I'm not driven by money but who I work with. I'm more likely to take roles in Australia than in Britain and America because I can go home."

One US film role she accepted was in The Rookie, a feelgood drama from the Disney studio. In the true-life story, she plays the wife of an injured baseball player (played by Dennis Quaid) who makes a bid for the big time after dropping out to teach in high school.

The character is only a supporting one, but came at the right moment for Griffiths. Intuition plays a large part in choosing roles. "It has a lot to do with what I've just done and how I'm feeling," she explains.

"I'd just done the first series of Six Feet Under, which I enjoyed enormously, but it explored large emotions on a daily basis, which is far more than a human being is meant to in a six-month period. So I wasn't looking for anything demanding or of an intense, psychic nature.

"The Rookie came along when I had been playing a character so ambivalent about herself, unsure about life and how to love, and who was in such a complicated relationship. It was just great to go on to play someone who's so clear about who they are and about their choices in life, for whom life is not an abstract idea but someone who keeps a group of people together. I liked that idea."

Mastering the American accent was less difficult than understanding baseball. She told the crew she'd been good at playing rounders at school, then had to explain the concept of rounders. But she points out that her role "didn't mean I had to be a rocket scientist about baseball".

She's committed to Six Feet Under for the next five years. Part of what interests her about the series is that it's probably the first mainstream TV drama to deal with religion and sex through, among others, a female deacon and gay undertaker. "It's very uncontroversial," she jokes.

* Six Feet Under is on E4 on Sunday and Monday at 10pm.

* The Rookie (U) is now showing in cinemas.