The issue was first reported by local newspaper Shanghai Daily, which reported that consumers in Shanghai have complained that some edible oils on retail in the city were not clearly labeled as GM foods.
These consumers have lodged a complaint with local authorities against the said manufacturers, saying that they were not inclined to buy GM food because of health concerns, but were misled into buying these oils, the news report said.
An official at the Shanghai Food Safety office confirmed over the phone that the office was in receipt of the news report, but could not confirm if it had received any complaints by consumers.
China has implemented GM food labeling since 2004, and can be considered the only developing country with an effective labeling policy in place, according to the International Food Policy Research Institute.
Under Chinese law, the sale of GM foods in the country is legal, but manufacturers must disclose clearly on the label that the product is made from GM food. However, as it stands, there is no clear definition of how big, small, of what color, and where the labelling should be.
The Shanghai daily report pointed out two brands of edible oil that it found in its investigation to be not clearly labelled as GM food - the Fulinmen soybean oil and the Jinlongyu blend oil.
The report added that both the oils had the words 'made from GM soybeans' too small to be legible for anyone, and almost unreadable for people of a senior age; in violation of the labelling law on GM foods. Also, the line on the label was mixed with other information, such as best-before date, and batch number.
Both companies did not respond to calls for comments on the issue as of deadline.