China is concerned about pesticide residue levels in wines and other food products, a government researcher said Monday.

Yan also pledged that the health authorities would tighten supervision over pesticides when he was asked to respond to an alleged wine contamination case during a Health Ministry press conference.

The Securities Market Weekly, a Chinese financial magazine, said in a cover story preview in its microblogging service account on Aug. 9, that 10 wine products from three Chinese winemakers were sample tested and found to contain excessive levels of pesticide residues - carbendazim and metalaxyl.

The story, due to be released in its Aug. 10 edition, was suspended due to unaccountable reasons. As of Monday, the report could not be found on its website and microblogging account. Calls to the magazine went unanswered.

High doses of carbendazim, a widely-used fungicide, can cause infertility issues and possibly lead to liver cancer, according to the magazine.

The preview sent a shockwave to the stock market, as yuan-denominated shares of Changyu, a leading Chinese winemaker whose products were listed among the samples, dropped by 9.83 percentage points on Aug. 10.

Following the preview, the board of directors of Changyu issued a statement on its official website on Aug. 11, saying all its products were up to national standards.

Song Quanhou, deputy head of the China National Research Institute of Food & Fermentation Industries, who signed the sample test report, told the media on Aug. 11 that the samples could not be identified as Changyu products and no past record showed the company's products were contaminated by pesticides.

According to the results of the sample test, the amount of carbendazim contained in the wine samples ranged from 0.00157mg/kg to 0.01942 mg/kg. This is below the maximum pesticide residue limits set by the EU and China, which are set at 0.5 mg/kg and 3mg/kg, respectively. The amount of metalaxyl in the wine samples ranged from 0.00211mg/kg to 0.01414 mg/kg, below the maximum pesticide residue limits in the EU and China, which are both set at 1 mg/kg.

Chinese Internet users have circulated the news via microblogging accounts and made hundreds of comments, with some of them questioning the ethics of news magazines, and others casting doubt over the country's scandal-hit food sector.

"Why kissing a fuss? If there's no report, there's no evidence," wrote a Internet user identifying himself as Li Junhu on Sina Weibo, a popular Chinese microblogging service.

"It's time for the winemakers to wake up and make a change, we need improved standards to regulate all the deadly food." wrote a microblogger called Xiong Yan.