CHIANG MAI, Thailand — The sex business has become increasingly difficult for Yai, the manager of a small brothel in this city in the north of Thailand, and the seven women who work for her. Last year, the police raided Yai’s establishment, and Yai, who asked that her real name not be used, was sentenced to a six-month jail term for running a brothel and employing illegal immigrants.

After Yai did her time, she and her employees, most of whom are immigrants from Myanmar (Burma) or China, quickly got back to their old line of work. But these days, they and the six other “girl houses” in the neighborhood do business differently. Potential customers who come in off the street only get to look at photos of the women, who wait somewhere else until Yai calls them on their cell phones to let them know a deal has been struck.

Strangers are eyed with suspicion, lest they turn out to be police or investigators from one of the faith-based anti-prostitution organizations that say they are trying to end what they consider sexual slavery. According to Yai, political pressure from such groups has led to a sharp increase in the number of raids. “In the past, authorities might consider receiving small sums of money to turn a blind eye,” she complained. “But now, they dare not do so.”

It’s unlikely that the raids will eliminate or even seriously hinder commercial sex work in Chiang Mai. But their effect on brothel operators threatens to wreak havoc with HIV/AIDS prevention efforts in the sex industry.

Where police once pressured brothel owners to insist that customers use condoms, they now seize condoms as evidence that sex is being sold. As a result, brothel managers such as Yai keep them off-site. And the brothel managers are increasingly reluctant to let HIV/AIDS activists in the door, out of fear that they’re actually police informants.

One of the faith-based activist groups feared by the sex industry is the International Justice Mission, based in Washington, D.C., which received a $703,000 U.S. government grant in 2002 to combat child trafficking and sexual exploitation in Thailand. The group’s Southeast Asia operations director, Sean Litton, said that the organization isn’t out to eliminate sex work. “Our mission in Thailand is to document situations where women and children, or men and boys, are being exploited in the sex industry due to deception or coercion,” he said. “That, and to mobilize their release, and get the perpetrator arrested.”

Along with its local partners, IJM investigated local bars and brothels, and information gathered was passed on to the authorities through those partners. Last year, IJM’s office in Thailand said it helped to “rescue” more than 100 victims of sex trafficking. Seven people were convicted of trafficking.

Litton insisted that IJM was not insensitive to sex workers’ needs and that it differentiated between volunteer sex workers and those who are forced into it. “Our mission is to fight trafficking, period. That’s it. Our mission is to rescue victims of trafficking, period. Nothing else,” he said.

But those types of investigations have come under intense fire from a number of Thai nongovernmental organizations, which questioned whether such “raid and rescue” operations help overcome the problem of sex trafficking. According to them, the operations create more problems than they solve.

Liz Hilton of the Empower Foundation, an organization that works to improve conditions for sex workers, fears that the raids hurt efforts to promote safe sex. She cites the example of a local bar that was raided by police, with help from faith-based investigators, in 2003. “They used to allow us into the brothel to deliver free condoms, but now the owner says no,” Hilton said. “We know that women there want our help, but what can we do? They don’t trust outsiders anymore.”

Meanwhile, Yai said that women in her brothel would continue to work in the sex trade, as long as poverty is the alternative. “It is impossible for us to stop, because we need money to sustain ourselves and our kids,” she said. “When police come here, we stop. When they go, we start again.”