The number of known cases of HIV - the virus that causes AIDS - on the mainland has reached 10,676, nearly 30 per cent up on last year's total. Intravenous drug users accounted for nearly two-thirds of the cases, said Ministry of Health Vice-Director Yin Dakui. Mr Yin was addressing delegates to the World AIDS Conference in Beijing. His ministry said ethnic minorities living in Yunnan, Xinjiang, Henan, and Guangxi Provinces made up 36 per cent of HIV carriers. Ministry sources said there were only 301 known cases of full-blown AIDS on the mainland, the Guangming Daily reported. However, there have been reports of fears that as many as 200,000 people may be unknowingly infected with HIV. Yang Fengrui, Public Security Bureau narcotics department chief, who was also at the conference, said levels of intravenous drug use - which went up from an estimated 148,000 users in 1991 to 540,000 by the end of 1997 - was a major obstacle to controlling the spread of AIDS on the mainland. HIV cases resulting from sex increased 15 per cent from 1996 to 1997 and 40 per cent in the first six months of this year. Officials have pushed for more education on sexually transmitted diseases and HIV transmission and called for swift and decisive intervention by government bureaus. Sexually transmitted diseases were the third most common type of infection on the mainland behind dysentery and hepatitis, the conference heard. The newspaper said the Government was putting aside about HK$1.2 billion per year for the fight against AIDS. Delegates vowed to continue to lobby for increased government action, particularly in relation to curbing the rate of domestic drug use. The authorities recently resolved to screen all prospective blood donors for HIV after concerns were raised over blood supplies becoming tainted.