Dramas based on historical details are always a political landmine.

Cheung admits now she was a little naive: the sisters she picked were, after all, not your run-of-the-mill 20th century Chinese women. The lives of the Soong sisters - Ailing, Chingling and Meiling - intertwine with recent Chinese history, not only because of who they married but because of their own contribution as well.

'I put it down to insufficient understanding of the complexity of the subject matter. I thought I was only writing a simple human story but the women were not simple women,' said Cheung.

'You know, under the British education system, we never studied that much Chinese history; everything after the Opium War was almost a blank.

'I never visualised that the two women [Chingling and Meiling] would be so important to Taiwan and China. I didn't know they were symbols of two nations and these two nations were at 'war' with each other.' The 'Soong sisters' were daughters of a western-educated missionary, Charlie Jones Soong, who helped finance the revolutionary movement of Sun Yat-sen. He had had the foresight to send the three girls to the US to be educated when most women still had bound feet in China. Their father's simple wish was to see them be the 'new women' of the 'new China'.

But history has a way of taking its own course. In the opening scene of The Soong Sisters is a caption that reads: 'Once upon a time in distant China, there were three sisters. One loved money, one loved her country and one loved power.' So it was that Ailing (played in the movie by Michelle Yeoh) married wealthy industrialist H H Kung (Niu Zhenhua), also the minister for the interior and finance, and became one of the richest and most powerful women of her time. Chingling (Maggie Cheung) embraced the Kuomintang ideals of her father's one-time ally Sun Yat-sen (Winston Chao Wen-hsuan) and married him - much to Charlie Soong's (Jiang Wen) disapproval - essentially making her the first lady of the Chinese republic after the overthrow of the Qing Dynasty. And, Meiling (Vivian Wu) would be drawn to military leader Chiang Kai-shek (Wu Hsing-kuo), who would one day found Taiwan's Nationalist government.

Like Charlie Soong, Cheung said her wish was simple too. She had not set out to make a historical epic and says The Soong Sisters, set between 1900 and 1949, should not be perceived as such.

In preparing for the film, both Cheung and her scriptwriter Alex Law read more than 200 books but all offered differing viewpoints. Mainland Chinese versions seldom mentioned Soong Meiling and most Taiwanese versions did not reveal her connection with Soong Chingling.

'Nothing was the absolute truth. Each version depended on who wrote it and who was in power. So I wrote my own. This is just a director's version of a part of that era,' she said.

'In a democracy, I always thought that it would allow and accept different points of view. I think I have been objective. As long as I kept to an objective viewpoint I felt there should be freedom of speech. This is Hong Kong, not Taiwan and China, and it would be the most neutral since we didn't have their historical burden.' But nothing in her dealings with the authorities had prepared her for the final cut. When Cheung - in collaboration with the Beijing Film Studios - first submitted the script for vetting in 1994, the propaganda arm approved it.

Once cameras started rolling on March 21, 1995, she was awarded full co-operation by the People's Liberation Army, the Chinese Navy and the Chinese Air Force who 'loaned' everything from marching soldiers to fighter planes and tanks. She even had free run of the old residences of the Soong family and Sun Yat-sen.

Filming for the epic finished in less than four months, and the final copy was submitted to the Propaganda Department in December 1995. By then, the committee that first dealt with the script had all been replaced by new members.

What followed was a year of pleading and negotiating, before Cheung's producers, Golden Harvest, told her that the committee had given their ultimatum. They wanted the whole ending cut as well as one significant scene where Meiling pleads for her husband's release in Xian, as well as other bits. Most of the objections were to scenes involving Meiling, who was persona non grata in China.

There was no room for compromise. Cheung was told to stick to Beijing's regulations or don't do it in China.

Cheung was dumbstruck. She had followed her approved script faithfully and only expected two scenes in which Chiang Kai-shek makes derogatory remarks about communism to raise problems.

'I told myself it could not be true. There was no way God would make me put so much time and effort into something to have it end like this,' she said.

'They wanted to end the film with just a caption that said the sisters never saw each other again. It would look as if we reached this stage and then ran out of money to finish the film.

'If I accepted that then I would have wasted everyone's efforts.' Scriptwriter Law says the pain and labour that went into the process of getting the project finished could never compare to the misery of having the film censored, even though he had the solace of being able to publish a book based on his screenplay this month. 'You feel so helpless because everything is done and there seems to be no connection [between what they fear and what you have done]. The worst is they always cut the best part. The best is always the most realistic and the part they like least,' he said.

But, having reached that far in a troubled project many thought she would have abandoned much earlier, Cheung made an unprecedented attempt to appeal the committee's decision despite advice to the contrary. 'They told me I was lucky to even have done the movie and said that no director had ever successfully appealed before,' she said.

'I also ran the risk of delaying it even further.' With the burden of everyone's contributions on her shoulders, Cheung made the trip to Beijing in winter, armed only with a limited knowledge of Putonghua. For a week, she sat in the falling snow outside the offices even though the committee refused to see her.

It was only when a female took pity on her and persuaded her superior, who then persuaded his superior, that Cheung was finally allowed to state her case.

'I think it was the director's sincerity that moved them. They are human beings after all and ultimately, not that difficult to deal with, especially if you explain honestly and they can see you have no ulterior motives,' Cheung said.

'I just asked them to give the film a chance. I told them the way they wanted it to end was not good for the cast and the crew, or the country's film industry. It would not be a responsible film.' Still, 18 minutes of footage - including Meiling's impassioned plea for Chiang - were snipped from the final version which still clocks in at 144 minutes. The Xian footage, retained by the Beijing censors, has somehow been lost.

'I guess that makes sure that even if anyone had the courage to defy them and put the scenes back in, no one would be able to see it,' Cheung said.

Ironically, it is this one scene that audiences will never see that Cheung most identified with.

'I felt like Soong Meiling taking on the whole Chinese army when I was facing that committee. Personally, I am very grateful to them. When I was at the most difficult hurdle, they offered help. They didn't need to; they didn't know me. I know they still censored the film but I understand they had to do that because of policy,' said Cheung, who still 'mourns' the exclusion of that scene.

'The balance of the whole film was tipped. It was a pity because Vivian was really very good; even the censors said that was the best scene.

'I think it was unfair to the actor because it was the climax of her performance. Throughout the show you see her maturing into an independent woman, and that scene was her making. The character was very complete, but now that the most powerful scene is gone, the character is a lot weaker.' Shanghai-born Wu, who now lives in Hollywood, agrees with Cheung. She had initially been drawn to the role of Meiling because of the character's development. While she says she respected the authorities' need to have 'some sort of politically correct statement', she is nevertheless disappointed her most compelling performance was left on the cutting room floor and felt that they could have been 'more flexible'.

'That scene would have been the climax; now what everyone will see will just be the foreplay,' said Wu, who never got to see the scene.

'That was how I paced myself to build that character. Everyone tells me how powerful it was. Had I known earlier [that it would be cut], I would have paced myself differently.

'We didn't do it as a political, historical documentary. We did it as a film where we fantasised about how these three sisters were. It's not as balanced now, and not as poetic [as Alex wrote it]. It's really a pity. To me it's a loss but to the director, it is a huge, huge loss.' With hindsight, Cheung said it was bad luck that The Soong Sisters had become so entangled in red tape. Had she done it earlier, she had no doubt it would have been spared its present fate.

'Censorship in the past two years has been tightened. I think if I went earlier, there wouldn't have been much problem. The film is neutral. I didn't pass judgment,' she said.

Despite doubts to the contrary, the director of award-winner Illegal Immigrant has always been confident The Soong Sisters would not face a total ban.

'It had already been made and so much money put in. They couldn't ban it because it involved overseas investment as well as their own,' Cheung said.

'The thing is how much you can negotiate back; how you can fight for the best version within the constraints of the regulations. Would it still be a complete film? If it were mutilated, I would rather the film not be screened, but this version is acceptable to me.' Cheung cannot envisage having filmed The Soong Sisters anywhere but in China, however, even though she always suspected there would be a few knots she would have to untangle. 'All the locations are in China; the Marco Polo Bridge is in Beijing and their residences are in Shanghai. If you made it anywhere else, there would not have been much meaning. Even if I had made it in Taiwan, there would have been another set of regulations,' she said.

But The Soong Sisters has apparently left its legacy in China, as the real-life sisters did. Cheung reports a new rule has been approved that all films about historical Chinese figures must now be made only by mainland Chinese directors and involve no foreign funding.

Despite everything, Cheung is still happy to have risen to the challenge of The Soong Sisters. Now that the battle is over, she can even see the upside of it all: the experience has been a crash course in politics, Chinese history and how to deal with the Chinese authorities.

'I am now an expert on how to manoeuvre in China,' she joked, before adding a more serious note: 'But I have also started to understand why China is so fearful of Western influence. Throughout history, there have been lots of times when Western powers have tried to control China especially during the Qing Dynasty. I can see why they are so paranoid about it and about student demonstrations because history has shown that student demonstrations can affect the political stability so much.' Her next movie, however, will most likely be about 'two people in a house' or something equally simple. 'You can't always make this kind of movie. You have to have the right cast, the right crew and the right support - and you have to be very committed. And, more importantly, there are not so many three years in your life that you can spend on one film.' The Soong Sisters opens in Hong Kong on May 8