BEIJING, Dec 6 (Reuters) Hollywood actor Matt Damon today defended his starring role in upcoming Hollywood film "The Great Wall", saying that accusations of "whitewashing", or the use Caucasian stars over actors of other ethnicities, were unfounded. "Zhang Yimou called me and asked me to be in his movie," Damon said in Beijing, referring to the film's director who joined him on a panel. Damon, also joined by co-star Andy Lau, said he would be "mortified" if he felt the accusations were merited. Critics decried the decision to cast Damon for the fantasy film set in ancient China. Damon said the issue was "very important" but drew a distinction between the practice and his role in "The Great Wall". "When I think of 'whitewashing' I think Chuck Connors playing Geronimo, that's whitewashing and that's unacceptable," he said, referring to a Caucasian actor who played the Native American chief Geronimo in a 1962 Western. Zhang, the acclaimed director behind "Hero" and "House of Flying Daggers", said the accusations were "unfair" to Damon. "Once you've seen the film you'll see it's not like that," he said. "It's a group of people, a group of heroes, and as it's set to the backdrop of a Chinese story so there are lots of Chinese heroes." "The Great Wall", out in China in this month and in the United States in February, features Zhang's trademarks of martial arts and saturated filters, and is centred around the mysterious origins of The Great Wall of China and what the wall's original purpose was. Strict censorship laws have prevented many Hollywood films from being released in mainland China. To counter that, US studios are co-producing big budget movies with Chinese investors. Hong Kong actor Andy Lau, an Asian super-star, said it remained to be seen whether Zhang's "mission" to bring Chinese culture to the West through film would succeed. "It might not be that successful in foreign markets, and I don't know whether people in our Chinese market will appreciate this style, but I think this is a new direction," he said. REUTERS JW BD1846