But a national uproar over several girls who danced topless in public during raucous celebrations at the recently concluded Songkran water festival has underlined the limits of acceptable behaviour and the nuances of public morality.

The dancers were filmed gyrating to thumping music in the heart of Bangkok on Friday, and video of it circulated widely. One clip was seen by nearly 1 million people before it was removed.

Reports of the episode shot to the top of Thai news websites, and the police began an investigation. Suddenly, one of Asia's most socially liberal societies showed a deeply conservative side.

''We will take legal action against them,'' a police official, Major-General Suwat Jangyodsuk, said of the dancers. ''This has damaged a traditional Thai ceremony. The charge is doing a shameful act in public by indecently exposing oneself.''

The Minister of Culture, Nipit Intarasombut, demanded that ''society come out and criticise'' the dancers, who he said should atone by reading books about traditional Thai celebrations to nursery school children.

Three girls aged 14, 15 and 16 turned themselves in on Monday. The police said they paid fines of 500 baht ($15.75) and were released. It was not clear whether their youth would help dissipate the surprisingly intense upset.

Thailand has rules against vice, and the government regularly blocks websites deemed to violate Thai values. But weak enforcement and a general laissez-faire ethos undermine such controls. The country has a long history of men frequenting prostitutes; Bangkok is home to hundreds of so-called saunas, where male clients do more than just soak in hot tubs.

Minutes from where the three dancers were filmed is the Patpong district, where women and men perform in sex shows and sex workers ply countless bars.

Chalidaporn Songsamphan, an associate professor at Thammasat University in Bangkok, said Thais were uncomfortable when sexuality was displayed in public, and the anger directed at the topless dancers was a way for people to channel their frustrations about wider social problems, like alcoholism, low student test scores and teenage delinquency.

''Thais need someone to blame,'' she said. ''It's easier than fixing problems.''

The New York Times