An AIDS group in China says a leading activist has disappeared in Henan Province.

Prominent AIDS activist Wan Yanhai says fellow activist Li Dan was beaten up by local authorities in Henan and taken to an undisclosed location Sunday night.

Mr. Wan, who heads the AIZHI Action Project in Beijing, says that at the time, Mr. Li and a colleague were on their way to a village where residents were planning a protest against the government's handling of the AIDS epidemic.

Mr. Li's colleague was later released, but Li Dan has not been heard from since then.

Mr. Wan says the central government is turning a blind eye on the suppression of AIDS activists by local authorities in Henan. Li Dan runs a charity helping AIDS orphans in Henan. He operated a school for AIDS orphans before it was shut down last month, reportedly after Mr. Li told authorities he was going to attend last month's World Aids Conference in Bangkok.

Li Dan's disappearance comes after four other AIDS activists from Henan were released Saturday from police custody. They were arrested as they were about to leave for Beijing to petition the national health agency about the plight of AIDS patients in the province.

Human rights groups accuse the Chinese government of trying to cover up the extent of the epidemic in Henan and of silencing AIDS protesters. In May, another Beijing-based activist, Hu Jia, was put under house arrest, preventing him from traveling to Henan where the U.S. ambassador Clark Randt was visiting.

Henan has one of the biggest AIDS outbreaks in China. In the 1990's, thousands of farmers became infected with HIV - the virus that causes AIDS - after selling blood to unsanitary blood collection centers.

Until last year, the government denied there was an AIDS problem in China. Now, Beijing says there are 840,000 people with HIV and 80,000 with full-blown AIDS. But the number is believed to be higher. The United Nations says the number of people with AIDS in China could rise to 10 million by 2020 if aggressive prevention measures are not taken.