Greenpeace claims two international brands from leading US food manufacturers, Kraft's Ritz crackers and Campbell's corn soup, contain genetically engineered soybeans.
The environmental group accused the food makers of having "double-standards" in their GE food policy.
Kraft and Campbell's Soup have committed not to use GE ingredients in Europe, but have not done so in China, they claim.
"We are demanding these companies not to sell GE food in China, as consumers deserve the same rights and safety standards everywhere," said Greenpeace campaigner Ma Tian Jie.
Health and environmental safety concerns over GM food crops manifested themselves in Chinese regulations implemented in 2002. The rules require all foods derived from GM crops to be labelled as such.
Arguably, it is not the label that is the issue for Greenpeace, but the use of GM ingredients by Kraft and Campbell. If they avoid using them in Europe, then they can do the same for the Chinese consumer, reason the campaigners.
The increasingly informed Chinese consumer is undergoing a raised awareness of the global GM biotech debate.
Set against the backdrop of the burgeoning Chinese food market, that quadrupled from under 100 billion yuan (€9.2bn) in 1991 to well over 400 billion yuan (€37bn) just ten years later, consumers are apparently starting to take a more strident position on GM foods.
A survey commissioned by Greenpeace on 600 respondents (from the 1.3 billion population pool) in Beijing, Shanghai and Guangzhou found that 62 per cent of participants were aware of 'GE food': this represents a 10 per cent rise on figures from a similar survey last year, says the environmental group.
On the issue of GM rice, a food close to the heart of the Chinese, Chinese consumers appear to be cautious, with 73 per cent of the respondents claiming they would opt for non-GM rice.
These findings come amid current discussions in China that could lead to the commercialisation of GM rice.
China leads the globe in rice production, and if it decides to clear the way, it would be the first country in the world to operate the commercial production of genetically modified rice.
Reports in the Chinese media state in December last year said that four varieties of GM rice were submitted for approval to a Biology Safety meeting, sponsored by the Ministry of Agriculture.
Recent figures from Cropnosis pitch the global market for biotech crops at €3.5 billion in 2004, representing a 15 per cent slice of the €24.3 billion global crop protection market in 2003 and 16 per cent of the €22.4 commercial seed market.The market value of the global biotech crop market is based on the sale price of biotech seed plus any technology fees that apply.