A kiss may be just a kiss in most of the Western world - and increasingly among India's Westernised urban elite.

But when it is on screen and between two of Bollywood's biggest heartthrobs, it still amounts to a whole lot more than a hill of beans. In fact, according to an Indian court, it could be considered a crime.

A criminal case has been filed against Aishwarya Rai, the former Miss World, and Hrithik Roshan over their on-screen kiss in the recently-released action blockbuster, Dhoom 2.

Shailendra Dwivedi, a lawyer in the central state of Madhya Pradesh, filed the suit last week and a local court has agreed to hear the case on December 11.

Mr Dwivedi accused the pair of lowering the dignity of Indian women and encouraging obscenity among India's youth.

Legal experts say the suit is almost certain to be thrown out by the court. But it nonetheless highlights the enduringly conservative attitudes towards public displays of affection in the country that produced the Kama Sutra more than 1,500 years ago.

The suit was filed a few days after another public storm over a photograph of Vasundhara Raje, the female Chief Minister of Rajasthan, air-kissing a woman at a World Economic Forum meeting.

Air-kissing is common among middle class Indian women and increasingly fashionable between men and women in the urban elite of major cities, especially Bombay. But the photograph, taken from an angle, makes it look like the two women are kissing on the lips.

Several Indian media outlets ran the picture alongside protests from politicians and commentators who branded it "obscene" and "vulgar".

Raghu Sharma, the vice President of the ruling Congress Party, even demanded that Mrs Raje, a member of a royal family and the opposition BJP party, resign over the photograph.

"The Chief Minister's act has been shameful, to say the least," he said. "Ms Raje has crossed all limits of public misconduct. She should be ashamed of her act."

That was widely viewed as cynical political opportunism. But analysts say both kissing controversies speak of the social gulf between India's increasingly Westernised middle classes and its highly conservative masses.

Today, most young middle class Indians are exposed to the same sort of films and television shows and computer games, laced with sex and violence, as their Western counterparts.

Thanks largely to the economic reforms launched in 1991, they also enjoy greater freedom than ever to date - and kiss - beyond the prying eyes of their parents.

"There's a structural change taking place in relationships because of urbanisation," said Dipankar Gupta, a sociologist at Jawaharlal Nehru University.

"The family no longer occupies the position it used to. You no longer inherit the family business or have land that's family property."

In most of India, however, kissing in public is extremely rare between heterosexual couples - and unheard of between homosexual ones. Even hand-holding is frowned on.

Bollywood movies only started showing on-screen kisses in the late 1990s and they were mostly sanitised smacks on the lips. In the last five years though, Bollywood has become more risque, featuring regular kisses, sex scenes and raunchy musical numbers performed by scantily-clad "item girls".

But India's film industry must still tread a fine line between keeping up with the times and offending its core audience. And whatever they do in front of the camera, female stars like Ms Rai remain fiercely protective of their reputations off screen.

In 2004, Kareena Kapoor, another famous Bollywood actress, sued a Bombay tabloid after it printed pictures of her allegedly kissing her own boyfriend in a restaurant.

Ms Kapoor, who had recently appeared in an advertisement covered in chocolate, said at the time that she belonged to a respectable family and could never have performed such an act in public.

Ms Rai and Mr Roshan were not immediately available for comment.

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