Iron Man has taken on some Chinese characteristics. At a recent ceremony in Beijing to promote Iron Man 3, lead actor Robert Downey Jr appeared wearing a Chinese garment and eating a local snack.

The film, which Downey describes as a "multi-cultural story about both the United States and China," will premiere in the two countries on May 3.

DMG, a Beijing-based company that cooperated with Marvel to produce the film, helped create a character called Dr Wu, a master of both Chinese medicine and modern science, played by veteran Chinese actor Wang Xueqi.

"Dr Wu is kind of the reason Tony Stark is still alive at the end of Iron Man 3," says Downey. "He is a bit a prophet of all the trials Tony Stark is going to go through. He is somebody who knows Tony is going wrong, but he will be there for him later."

Wang, 67, said he never imagined he would act in a Hollywood film.

"I did have many dreams but playing in a Hollywood film was never one of them," he says. "I am thankful for the good timing and precious opportunity."

"This is the first time a Chinese character has featured in a Marvel film, which is amazing," adds Wu Bing, president of DMG. "Introducing Chinese culture to the world is the core mission of our company."

Popular Chinese actress Fan Bingbing gets a role, too, but the film has two versions and the one with her playing a nurse will only be released in China.

Beijing is one of the film's locations, and the production filmed in the city for a week in December.

The film's Chinese elements also include product placements for TCL, China's leading television and mobile phone manufacturer.

According to the Motion Picture Association of America, China replaced Japan as the world's second-largest film market in 2012.

The first two Iron Man films were both released in China. Iron Man was the fourth-highest grossing foreign film in China in 2008 and Iron Man 2 the sixth in 2010.