SHANGHAI - A share listing plan by a company that sells tonics made with bear bile is provoking a storm of online criticism in China from animal rights groups, celebrities and ordinary Chinese.

Reports Friday said dozens of well-known entertainers, writers and other celebrities signed a petition to the China Securities Regulatory Commission urging it to withhold approval for the initial public offering by Guizhentang, a Chinese medicines maker. The company is awaiting approval for a share listing in Shenzhen.

Hundreds of thousands of comments on "weibo," the Chinese version of Twitter, blasted the company for extracting bile from the bears.

A photo on the front page of the state-run newspaper China Business News on Friday showed a satirical photo montage of a caged bear, its nose bloodied, with a picture of the head of the China Association of Traditional Chinese Medicines, Fang Shuting, quoted as saying that bears are "very comfortable" while the bile is extracted.

A spokesman for Guizhentang, who gave his surname as "Xu," refused comment.

"It is not the right time for an interview now. We will let you know when we want to do an interview," Xu said.

Animal rights are gaining increasing attention in China, with public figures like basketball star Yao Ming and actor Jackie Chan speaking out against eating shark fins and other customs that many view as cruel or a threat to endangered species.

The petition to the stock watchdog from more than 70 celebrities and environmental protection groups seeks to block the IPO and urges the use of synthetic substitutes for bear bile, which is a digestive substance made in the liver and stored in the gall bladder.

The main active ingredient in the bile is ursodeoxycholic acid, or UDCA. It is thought to act as an anti-inflammatory and is used to treat gall stones and liver ailments.

Chinese media reports Friday cited Fang as defending Guizhentang's bile collecting practices in a news conference in Beijing, after visiting its facilities in southeast China's Fujian province.

"Collecting bile is like turning on a tap. It's painless, natural and simple. I didn't see bears suffering in the process," Caijing magazine quoted Fang as saying.

"After the bile is extracted, bears can still drink milk and honey and have fun in the farm."

The reports cited Fang as saying China has 68 licensed bear farms and more than 10,000 bears farmed for their bile, which can cost up to 4,000 yuan ($635) a kilogram.

Animal rights groups contend the practice of bear bile farming is cruel because the bears are confined to small cages and milked of bile through catheters inserted into fistulas, or permanent wounds, in their gall bladders.

They say that antibiotics used to counter chronic infections from the practice, and other contaminants in the bile, also pose a hazard to human health.

One such group, Animals Asia, has been working to close down such farms and rescue the bears. It runs a sanctuary for those that survive in southwestern China. It has also worked with local groups to lobby for the industry to be outlawed.