Naomi Watts

When Forbes magazine recently published a list of the most bankable actresses in Hollywood, Naomi Watts was the surprising name at the top.

It's a financial magazine, so the list was compiled using a rather dry return-on-investment test. It was calculated that the 41-year-old actress appeared in films that earned $44 (€29) for every buck that she was paid. A list of her recent credits includes The International, King Kong, Funny Games, Eastern Promises and The Painted Veil.

The criteria used by Forbes are strange, but it seems that the real beneficiaries are the producers of the actor's forthcoming films, who will be rubbing their hands together, relieved that they've nabbed a star before their pay packets inevitably rocket skywards.

Yet speaking at the San Sebastian Film Festival, which hosted the European première of her latest film, Mother and Child, directed by Rodrigo Garcia, son of the Colombian author Gabriel Garcia Marquez, Watts says that she earns enough money from doing the occasional big-budget film and appearing in advertising to not worry if the wage for her primary job isn't as high as it could be. Not only that – for the right role she's willing to take a pay cut.

"I'm no spring chicken," she announces in her forthright manner. "I'm really honoured to be offered contracts to promote goods. When things like that come along, you're really flattered and also very relieved – because to get movies like Mother and Child made, it helps to be able to say, okay, I'm going to go off and work for a number of weeks and be paid nothing basically, and then be able to fall back on endorsements."

The family title of her new film seems apt as the actress recently had two boys, now aged two and nine months, with the actor Liev Schreiber, who was her co-star in John Curran's 2006 drama The Painted Veil.

She says of her own experience with motherhood: "I'm a mum and the whole concept is science fiction. It is just bizarre. I still can't believe it when I look at my children that they came from one little moment. They're so surprising and endlessly fascinating and soon they're going to have problems. Now they're just innocent little beings, learning and growing, but soon they'll be all f**ked up." The actress catches herself and laughs, before quickly apologising. "Sorry I didn't mean to go there."

This is the type of cynical statement that her character, Elizabeth, continually makes in Mother and Child. As has become the norm for films associated with Alejandro Gonzalez Inarittu, who is one of the producers, and previously directed Watts in 21 Grams, the film is split into three stories that eventually intersect. Watts plays a lawyer who puts her career before having a family. She seduces her married boss, played by Samuel L Jackson, while also sleeping with a neighbour whose wife is pregnant. The character sees the dark side to every situation, and has not yet come to terms with the fact that she was given up for adoption as a child.

On putting career before family, Watts states: "I can relate to that. At the beginning, when things were taking off for me in America, I was on the treadmill and I didn't want to have a relationship particularly. I wanted to travel. I come from a background, that was not a troubled childhood or anything, but there has been some sadness, perhaps that I didn't want to face and work seemed like a good option. But now I've slowed down and have a family. When I met Liev things changed."

Though she was born in Shoreham in Kent, Watts was brought up in Australia. Her father, Pete Watts, a sound engineer for Pink Floyd, died when she was seven. Her mother left England before settling in Australia with her son and daughter. Watts began acting and appeared alongside her friend Nicole Kidman in Flirting. She watched as her friend's career went into the stratosphere while her own seemed to stagnate, a state that she captured in the low-budget Australian picture Ellie Parker, in which the frustrated actress played a frustrated actress.

However, that film was shot in 2001, the same year that David Lynch cast her in Mulholland Drive. Almost overnight, she became a household name.

In recent years, Watts has garnered the nickname 'The Queen of the Remake', having appeared in both adaptations of Hideo Nakata's Ring films for the American audience, Peter Jackson's box-office smash King Kong, and Michael Haneke's Funny Games.

"People keep asking me, "How come you've done so many remakes?'" she says. "And I keep saying it's because there are no good ideas and no great roles out there."

She is referring to the lack of good roles for women, and says that one of the things that attracted her to Mother and Child was that it revolved around three strong female characters.

She adds: "It's rare to come across great writing for women. You can't just leave it for writers to come up with something – you have to be a bit pro-active in terms of reading everything that is sent to you and reading newspaper articles. Not that I've been especially proactive lately, with children."

It's a damning indictment of the entertainment industry that an actress like Watts cannot find roles of a high enough calibre. She is not even sure what she will make next but she is excited about two other projects that she has just finished working on.

"One was with Woody Allen, which was a great experience. He sent me the script, but I didn't meet him until the day we started shooting which was unusual. Another film, that hasn't got a title yet, is based on the story of Valerie Plame, who was surprisingly revealed to be a CIA agent by the Bush administration. She wrote a book called Fair Game and that is the title that we are using for the film for now."

To prepare for the role, Watts had a brief meeting with Plame. "She is an amazing woman and I didn't try to do too much. This film came about so quickly and I didn't spend enough time with her to take on every facet and mannerism. She is such an extraordinary woman."

Her life has changed so much in recent years that it does now take extraordinary women and roles to convince her to leave her kids and pursue her occupation.

'Mother and Child' is out next year