Authorities in northeast China's Jilin province are investigating a case in which five wild bears were reportedly poisoned by poachers on the Changbai Mountains, a popular summer resort destination.

On Monday afternoon, local police and workers from the administration of the Changbai Mountains nature reserve were dispatched to patrol the area where the poisoning allegedly occurred, according to Cai Hongwei, deputy director of the administration.

The second on-site probe started Tuesday morning, Cai said.

Cai vowed a thorough investigation into the case and "serious treatment" for any poachers who are found to have operated in the nature reserve.

On Sunday, wildlife writer Hu Donglin posted an article on Sina Weibo, a popular Chinese microblogging site, saying five bears, including three cubs, were poisoned on the north slope of the Changbai Mountains.

Hu also uploaded a dozen photos showing the remains of animals that he identified as four black bears and a brown bear, adding that their gallbladders and paws had been removed and were unaccounted for.

Hu said he learned about the tragedy from local residents in early June, finding the site of the incident after an arduous search.

Bear paws are a delicacy in China. Bile from the gallbladders of bears is used in traditional Chinese medicine to treat a range of illnesses. Demand for both has resulted in rampant poaching, despite the government's efforts to bring the bears under state protection more than two decades ago.

Poachers can obtain at least 20,000 yuan (3,174 U.S. dollars) for selling bear parts on local black markets, Hu said.