More than 200 migrant workers stood with hesitation and embarrassment at first, with some watching from building windows, but they later seized all 6,000 free condoms given by Chaoyang District Disease Prevention and Control Center, which organized the campaign.

Doctors from the center asked the workers about transmission channels of the disease, but most of the workers on the site had little knowledge.

They asked the doctors about AIDS symptoms and the government's policy on treatment.

"I want to know about AIDS for the sake of my health and my family's health," said 25-year-old Xie Lingdun from central China's Henan Province.

Other workers wanted to know about AIDS, but did not want to take the test. "We are worried that the test results would show up HIV positive," said 21-year old Gao Baoliang.

Center staff took blood samples from more than 200 workers, promising to give the results to workers in private in about two weeks, said Li Dongliang, an official with the center.

Migrant workers accounted for 77 percent of Beijing's new 633 HIV carriers this year, statistics from the Municipal Health Bureau show.

"Unprotected sex is a major cause of workers contracting the disease," said Li. "Most workers visit home once a year, and some pay prostitutes to deal with sexual deprivation in the lonely days away from home."

An earlier survey by the Ministry of Health showed that 88 percent of migrant workers suffer from sexual deprivation to some extent.

"Among my peers, at least three out of ten go to prostitutes," said Ma Jianhua, 27, from Emeishan city in Sichuan, adding that some take greater risks as they do not like to use condoms.

According to Ma, a prostitute costs 50 to 150 yuan (6.4 to 19 U.S. dollars) in the area, while their daily pay ranges from 40 yuan to 200 yuan (five to 25 U.S. dollars).

"We can see at least a dozen prostitutes aged from 25 to 40 around the construction site in the daytime, and more will show up at night," said Ma, adding that boredom drove many men to prostitutes.

Experts had proposed more conjugal rooms on construction sites and paid holidays for workers to visit their wives, said Wang Hui, a campaigner and official with the local community government.

"We will offer AIDS prevention classes and show video materials on AIDS awareness and prevention," said Wang.

Data from the Health Ministry shows the number of officially reported HIV/AIDS cases rose to 183,733 nationwide this year, up nearly 30 percent from 144,089 at the end of last year.

As of October, about 185,000 migrant workers from 386 construction sites in Beijing had received AIDS prevention education, according to the statistics from the center.