Internet companies will be blamed and punished if they know food and medicine sold on their websites have problems or receive consumer complaints, a new judicial interpretation said.

Shoppers who are harmed by food or medicines sold online can sue the Internet companies first if the companies do not provide the manufacturer's contact information, the Supreme People's Court said in an interpretation issued on Thursday.

If online companies are aware the food and medicine makers are using the Internet companies' websites to harm consumers but do not take measures, both parties will assume joint liability, the interpretation said.

"The new rule aims to stimulate websites to be more selective about manufacturers, especially of food and medicine, they make accessible in order to regulate the market and reduce disputes," said Sun Jungong, spokesman of the court.

From 2010 to 2012, Chinese courts heard 13,216 cases involving food or medicine, or 6 percent of consumer disputes, according to the top court.

Meanwhile, complaints related to online shopping have also been growing quickly, the China Consumers' Association said.

In 2012, 20,454 complaints were filed, and in the first half of 2013, the number stood at 18,471, the association added.

"The fast development of e-commerce compels us to make more specific rules to help judges handle related disputes," Sun said, adding that the interpretation will take effect on March 15, when the revised Chinese Consumer Protection Law is passed.

Liu Junhai, who participated in drafting the interpretation, said putting partial blame on the online giants will push them to improve supervision on their websites and provide a safer buying environment.

"Some Internet companies think they are a third party, supplying a shopping platform for people, only caring about benefiting from the online shop owners, manufacturers and customers, instead of considering whether the products on their websites are safe or qualified," he said.

So these online giants should be blamed for their negligence, according to Liu.

"The online providers had better boost the registration threshold for food and medicine producers, checking their business licenses and product qualification certificates carefully," he suggested.

Liu added that online companies can file an appeal if they can prove they have no relation with the manufacturers of a questionable food or medicine.

Taobao, China's largest customer-to-customer site, has noticed the new directive and is revising its rules for after-sales services accordingly, said Zhou Yulei, a customer relations officer at Alibaba, parent of Taobao.

Zhou said Taobao has always precluded third-party sales of medicine and medical instruments.

"Taobao simply provides a digital display of the medicines, and customers are encouraged to buy via the drugstore by redirecting them to drugstores' websites," he said.

The e-commerce platform has imposed strict requirements for food vendors. To register a virtual shop, merchants should provide a food circulation license issued by the country's food safety regulator, as well as an authorization form from the brands concerned. For imported foods, vendors also need to submit copies of their Customs clearance certificate.

Shen Ziying, a regular Taobao shopper, said the rule is "heartening news" for food lovers like her.

She said she had bought two boxes of stale pineapple cakes on Taobao and it took her three days to talk the vendor into giving her a refund.

"The rule will save me time arguing with the merchant. Now I just wonder what kind of forms I need to submit to the website to return or refund. I hope it won't be too troublesome," she added.