BEIJING - A draft national standard for the catering industry has proposed a "tracking mechanism" for all kitchen waste as a way to break the illegal supply chain of "gutter oil."

"Gutter oil", or reprocessed cooking oil (sold as edible oil) illegally produced from leftovers dredged from gutters, has caused major public concern over food safety in China in recent years.

The draft, published on the website of the health ministry on Tuesday to seek public comments, stipulates that catering service providers should set up a comprehensive management system for kitchen waste.

It requests such providers sign contracts with dealers in kitchen waste who will be required to obtain authorization certificates.

A detailed record of each waste disposal should be kept, specifying its type, volume, receiver and expected use, the draft reads.

Such records are also required to be reported to the administering authorities on a regular basis.

Reprocessed waste oil from restaurant leftovers can legally be used in making biodiesel fuel or animal feed in China.

The window for members of the public giving their opinions on the draft closes at the end of January, 2012.

Chinese police launched a high-profile campaign in late August against food safety offences including making and selling gutter oil, and they believe they have effectively curbed the illegal practice.

However, the country's food safety authorities are still struggling to find a reliable method to differentiate qualified edible oil and reprocessed gutter oil.