Compared to African countries and other developing nations such as Vietnam where patients struggle to get any treatment, China's promise to provide free drugs to all patients is praised by international experts as a significant step forward.

But while the government is providing drugs to all patients it finds who need them since it launched the program in 2003, it has provided treatment to only 26,000 people despite an estimated HIV/AIDS population of 650,000 by the end of 2005.

Zhang said that is because China has found only a fraction of those infected.

"We have records for only 160,000 people with HIV/AIDS and that's cumulative from 1985 and we don't know where many of these people are," Zhang said.

Some are commercial sex workers who registered using fake names, making them hard to track down, Zhang said.

Others, including some people who sold blood and some lying on their death bed, refuse to be tested for fear of discrimination against themselves and their family, villagers and AIDS activists have told AFP.

Children have been especially hard to find, Zhang said.

"Definitely there are a lot of kids who haven't been found and a lot of kids who died without knowing they had AIDS," Zhang told AFP.

According to official figures, China has around 1,880 children with AIDS. Most of the children were found in AIDS villages in central China's Henan province where many farmers were infected from selling blood in unsafe schemes.

They were found during widespread testing of people in the hard-hit villages.

Few kids have been found in other areas including China's most infected AIDS regions, such as Xinjiang and Yunnan, Zhang said.

The government is meanwhile stepping up efforts to obtain children's AIDS medication, which it currently does not provide.

Other than 200 children getting child treatment donated by the Clinton Foundation, and another 50 from Medecins Sans Frontieres, children with HIV/AIDS in China either receive no treatment at all or have to resort to taking adult formulations, which is not ideal because the side effects are too strong.

"Many kids react strongly to adult formulation drugs. They vomit or become feverish," Li Qimin, deputy director of China's National Committee for the Care of Children (CNCCC), was quoted by Xinhua news agency saying last week.

The adult pills are cut in half for the children -- not a good method because the components of a pill are usually not distributed evenly.

Health experts estimate the real number of infected children in China is more than 9,000, Xinhua news agency said.