Gay men from Hong Kong are more likely to have unprotected sex across the border than in their home city, according to new data. Researchers found similar behaviour patterns among heterosexuals from Hong Kong on the mainland, where HIV is being fuelled by drug users injecting themselves and through sex workers. They said cross-border HIV prevention should be given more resources. 'It is unfortunate that the Aids Trust Fund in Hong Kong is not supporting HIV work that is implemented on the mainland, where risky behaviour is taking place,' said the study's team leader, Joseph Lau Tak-fai, director of the community research programme on Aids at Chinese University. The survey by university epidemiologists looked at the sexual behaviour of 283 gay men who had sex with other men in the past six months. Fifteen per cent said they had been to the mainland during this period to have sex. 'These men are likely to be older - aged from 46 to 69 years old - and are less educated,' Professor Lau said. Seventy-five per cent of those who travelled to the mainland for sex were more likely to have sex with male prostitutes, while 26 per cent of the cross-border travellers said they had sexually transmitted diseases. Eighty-three per cent of those who go to the mainland said they had engaged in unprotected sex, compared with 57 per cent of Hong Kong men who have sex with men in their home city. 'The data suggests that gay men who are crossing the border are at high risk of contracting HIV,' Professor Lau said. He said he believed men who crossed the border for sex had less access to partners in Hong Kong. Professor Lau noted that the Chinese Centre for Disease Control estimated that 11 per cent of HIV infections on the mainland were due to homosexual sex. But the professor said this was an underestimation because only one out of 200 HIV surveillance centres across the mainland was dedicated to homosexuals. Professor Lau said the same sexual behaviour had been reported among heterosexuals who went to the mainland to have sex with prostitutes. 'The heterosexuals have reported lower use of condoms when they are on the mainland. As a result, cross-border travellers have reported a higher incidence of sexually transmitted diseases. About 20 per cent of them contracted such diseases in the past six months.'