Bangkok - Thailand's famed entertainment industry is set for a body blow from Monday with midnight closures ordered for most nightspots, but as the witching hour neared, venue operators were unsure whether the crackdown would be enforced.

In a move that many bar owners say signals the possible deathknell for their businesses, the government announced this month it would strictly enforce regulations requiring nightclubs, discos, go-go bars and massage parlours to lock up by midnight from March 1 if they are outside designated zones.

Bangkok has three such zones, where venues will be allowed to remain open up to 2am, but for bars and nightclubs outside those areas the prospects are grim.

"Basically my business starts at midnight," said an exasperated David Jacobson, a partner in Bangkok's long-running New York-style nightclub Q Bar.

"It probably means we won't be able to survive. We'll try, but I'm not too optimistic," he told reporters.

Jacobson was quick to laud Prime Minister Thaksin Shinawatra's efforts to clean up what the bar owner called Thailand's "reputation as the cheapest destination for sex and drugs and rock and roll".

But he said the premier had gone about the campaign the wrong way, allowing late night closures at the famed red-light district of Patpong, the New Petchaburi area known as RCA popular with Thai teens, and Ratchada Phisek which teems with massage parlours and karaoke bars.

"It doesn't make sense to approve a sex zone, an underage kids zone and a massage zone," Jacobson said.

"They should be shutting down the three zones they've approved and let the rest of the city operate, but they seem to have it ass backwards."

The Thai press has pounced on the issue, with the Bangkok Post offering a withering critique of the plan.

"The fact that RCA is in the extended-hour zone at all makes a mockery of the whole exercise as it is a well-known hotbed of underage drinking, drugs and fighting - precisely the evils the government says it is trying to wipe out and wants to use a 10pm curfew to do so," the daily said in an editorial.

Thailand in February slapped a nationwide nighttime curfew for all youths under 18 in an effort to prevent them from roaming red-light districts and engaging in crime.

Flamboyant massage-parlour tycoon Chuwit Kamolvisit has railed against the plan, blasting government ministers as hypocritical and warning the new rules will drive away tourism, Thailand's biggest money-spinner, and put thousands of people out of work.

"They want to promote Bangkok as a 'fashion city', a city that never sleeps, but now they close at midnight," he told reporters.

Early closing could merely drive nightlife including prostitution underground, he said.

Chuwit's history lesson alludes to the massive changes Thailand has witnessed in recent decades.

An agrarian society half a century ago, the kingdom has undergone a transformation to modernity, particularly in Bangkok, a city of 10 million.

The battle over closing hours is seen as one front in Thailand's tug-of-war between traditionalists and progressives.

The nightlife crackdown began in August 2001 under the stewardship of the government's "Mr Clean", then-interior minister Purachai Piemsombun, and ended the free-wheeling ways of Bangkok's bars and clubs which used to shut at dawn.

The initiative was firmly backed by most Thais who were alarmed by the epidemic of drug use among Thai youth and the easy availability of drugs.

But even as nightclub owners howl in protest over the tightening of the morals campaign, there is doubt over whether the closing rules will be enforced.

Metropolitan police contacted just 36 hours before the zero hour said they were in the dark about how to proceed after they learned the ministry had proposed new regulations that could maintain the current closing time of 2am for all venues.

"Everybody is waiting for that last moment to see what happens," bar owner Jacobson said. - Sapa-AFP