SHE is built like a ballerina and relative to most boxers she's as tall as Thumbelina, but here is Michelle Yeoh, the empress of the martial arts epic, demonstrating how to throw a punch.

"They always wanted you to hit harder," she says of filmmakers in the early days, "but it wasn't about hitting harder, it was how you threw the punch." One had to hold on until the last minute, then unleash the power. Her arm, lean as a branch in winter, whips from her waist in demonstration.

When it comes to using brains rather than brawn, Yeoh would be among the first to defer to the subject of her new film, The Lady. A portrait of Aung San Suu Kyi, the Burmese democracy leader who lived under house arrest for more than 15 years before her release in 2010, the Luc Besson-directed biopic stars Yeoh as the Nobel Peace Prize winner.

Playing someone called "a hero of mine" by President Obama would be daunting to any actor with a sense of history. Yeoh recalls the award of the Nobel in 1991. "I was living in Hong Kong and there was this woman getting the Nobel peace prize. As an Asian woman you think how did that happen? She inspired many people around the world."

When Yeoh heard a film was being put together she was determined to become involved. "I knew that this had to be mine. The lucky thing was they were looking for me as well."

The film shows the wider context of Suu Kyi's stay in Burma, in particular how the military kept her and her husband, the Oxford academic Michael Aris, apart. In later years he was denied permission to visit, even when he fell ill, while she was afraid to leave the country, knowing the junta would never allow her back.

"It is one of the most incredible untold love stories," says Yeoh, 49. Though some might question the focus on the personal as much as the political, she believes telling the story that way has its advantages.

"Our greatest achievement will be that after the film you go and look at what Burma is about, the real politics. As filmmakers, as storytellers, we need to bring to you the human drama, the emotions. When you are given statistics and facts you don't remember them, but if I can make you feel, you will remember that for a long time."

What would "the lady", as the Burmese people affectionately call Suu Kyi, make of a film being made about her? "Not very much I'm sure," says Yeoh, smiling. "She would say I'm not that interesting, why would you want to spend two hours on me? Her attention has always been on somebody else."

Yeoh can speak with more authority than some on what Suu Kyi might think because she managed to get into Burma for a day to visit her. She found "a very warm, genuine person, a good human being" who was quick to laugh, to tease, and above all to listen. "She's very curious. You bring the outside world to her."

Yeoh had a tiny taste of the junta's capriciousness when she tried to visit Suu Kyi again in June. She got as far as passport control in Rangoon before being deported. "I couldn't believe it." Waiting to get back on the plane, Yeoh was tempted to rejoin the passport queue and try her luck again. Though she didn't in that instance, this can-do, or will-try, spirit stretches back to the time when a back injury ended her ambition to be a ballet dancer.

The consultant broke it to her gently by asking if she had ever thought of doing something else. "I was in tears, sobbing like a baby. You can't come to grips with it, 'What do you mean I can't dance?'"

She re-trained as a choreographer and was about to start her own ballet school in England. A trip home to Malaysia caused those plans to be cancelled. Unbeknown to Yeoh, mum had entered her into the Miss Malaysia beauty contest.

"In the end I said okay, just to get you off my back I'm going to go, and if I don't get in I never want to hear about this again. But I always listen to my mum at the end of the day because there is some wisdom in it."

Yeoh was crowned in 1983. Mum was right: Yeoh did get to travel and see her own country. The experience must have added to her have-a-go attitude, because when a friend recommended her for an advert in Hong Kong with Jackie Chan she went for it. That led to her first film, Owl versus Dumbo (1984) and a choice: stay in the comedy part of action comedies, or join the boys on the action side. If she stayed in the comedy half the future was clear. "The women were the damsels in distress. We needed to be rescued. Every day."

Action films were not that strange a territory for a dancer. "As far as I was concerned this was a huge musical without the music. Everything was choreographed, everything had timing." She still had to convince her male co-stars and stunt men that she could cut it.

"I was in sheer heaven. I was getting back to the physical things that I loved, discipline, training. At the beginning a lot of them folded their arms to watch, 'Show us what you can do'. I thought I have to show them that I am willing to try, [to handle] whatever they throw my way. Even if I don't get it right they have to see I'm willing to learn and that I'm not afraid to take the blows. Because there was full impact, and if you didn't know how to do it properly it hurt."

Injuries? Yeoh's had a few, including torn tendons, cracked ribs, and so many bruises on her one director thought she was covered in mud. The worst came on 1997's Stunt Woman when she fell 18ft from a bridge and landed on her head. "I'm lucky I didn't break my neck."

Her efforts paid off with a part in Tomorrow Never Dies, in which she was hailed as "the strongest Bond girl in years". From there it was a scissor leap to Ang Lee's epic, four Oscar-winning Crouching Tiger, Hidden Dragon (2000), Memoirs of a Geisha (2005) and Danny Boyle's science fiction thriller Sunshine (2007). I wonder if she has found it difficult, as a Malaysian actor, to get a mainstream break in America.

"It is hard. As an actor everyone will tell you it's difficult to get a good role in the first place. And yes when you are in a minority it's even more difficult because you are not the mainstream."

That's why filmmakers from the East, she says, should be focusing on their own tales (she has her own production company). "We have so many stories to tell. We have a very rich culture and an incredible landscape so we should build on that rather than wait for Hollywood to come." Spoken like a true fighter.

The Lady opens on December 30.