A group founded by well-known imprisoned Chinese activist Hu Jia to work with AIDS patients and orphans said Thursday it is closing down after increasing pressure from tax authorities.

Beijing Loving Source appears to be the latest casualty of official suspicion and harassment of activists and groups that take on sensitive subjects, even though the government recognizes AIDS as a legitimate concern.

Earlier this year, the founder of another prominent AIDS advocacy group, Wan Yanhai, fled to the United States after receiving dozens of intimidating phone calls from police. And the government startled most privately run aid groups in March by deciding to regulate overseas donations that many say keep them alive.

China's leaders are realizing that outside help is needed for the country's deep social welfare problems, but worry the work of independent activist groups could turn political.

Beijing Loving Source worked with the United Nations and Oxfam on projects to promote AIDS education and care in rural areas.

Hu's wife, Zeng Jinyan, announced the group's closure Thursday in a posting on her website.

Zeng said she couldn't forget the "profound lessons" from the closure in 2009 of legal aid group Gongmeng, which took on some of China's most politically sensitive cases. The Beijing tax bureau fined Gongmeng 1.4 million yuan ($206,000) for failing to pay taxes — widely seen as a dramatic move to restrain the country's activist lawyers.

Now the same tax bureau is pressuring Beijing Loving Source for a detailed audit, Zeng said.

She said the bureau didn't usually concern itself with groups as small as her husband's.

Hu, who with Wan pushed hard for authorities to deal with AIDS more openly, is now serving a 3 1/2 year prison term on sedition charges for his outspoken ways.

China's struggle to control the rapidly growing number of grass-roots groups, fueled by an improving economy and a growing ability by citizens to reach out to others, has not been graceful.

Zeng said she hoped the group's volunteers could carry on the work it started.

"We're very moved. Without the help of volunteers, at least more than 100 AIDS orphans could be living on the streets," she said in the announcement on her website.

The main phone number for Beijing Loving Source was already turned off Thursday evening.