State officials in China are unsure which is more dangerous about downloadable versions of Ang Lee's spy thriller Lust, Caution — the computer viruses or the sex.

The hundreds of downloadable versions of the film available in China are embedded with viruses, officials warned Monday.

Chinese actress Tang Wei arrives in Venice this August for a screening of Lust, Caution.
(Andrew Medichini/Associated Press)

Not only that — it could be unhealthy to attempt some of the sexual positions shown in steamy scenes between mainland actress Tang Wei and Hong Kong actor Tony Leung Chiu-wai.

Lust, Caution, about a group of students trying to assassinate a corrupt official working with the Japanese during the Second World War, has been a big hit in China.

The version approved by Chinese censors has had seven minutes of explicit sex scenes removed, but still reaped 90 million yuan ($12 million) in its first two weeks.

Chinese moviegoers in southern China are also crossing the border into Hong Kong to see the full version and hundreds of sites are offering uncut versions over the internet.

China's Internet Information agency, a state-run regulator, is warning that downloadable copies of the movie are embedded with viruses that steal users' personal information and can wipe out data.

About 15 per cent of downloadable movies have viruses attached, the agency warned.

"Hackers are taking advantage of popular entertainment hotspots for movies and music to attack personal computers and spread viruses," said a representative of Beijing software firm.

At the same time, Xinhuanet, an online portal for the official Xinhua news agency, has issued a warning from Chinese doctors about the acrobatic sexual scenes in Lust, Caution.

"Most of the sexual manoeuvres in Lust, Caution are in abnormal body positions," said Yu Zao, a deputy director at a women's hospital in Guangdong.

"Only women with comparatively flexible bodies that have gymnastics or yoga experience are able to perform them. For average people to blindly copy them could lead to unnecessary physical harm," Yu said.

Lee, who won the best director Oscar in 2005 for his gay cowboy drama Brokeback Mountain, made Lust, Caution in Mandarin and the story is set in Shanghai and Hong Kong during the war years.

He refused to cut the film for the U.S. rating service and earned an R rating because of sexual content. It has an 18A rating in Canada.

However, to get the film shown in China, he agreed to cut on-screen sex and other scenes.

Lust, Caution won the Golden Lion, the top award at the Venice Film Festival, earlier this year.