As much as 80 percent of the edible ice cubes in Beijing's shops and restaurants come from "illegal" factories, National Business Daily reported.

Only six manufacturers have production license for edible ice in the capital, making the total output valued at 100 million yuan ($16 million) in the summer season.

But the output of the whole market is valued at?500 to?800 million yuan, which means at least 80 percent of the ice come from non-qualified factories, the report said.

Edible ice companies must have a QS, or Quality Standard identification since 2005. And it costs at least 30,000 yuan ($4,893) to cover the certification besides building laboratories and hiring inspectors, according to an agency for quality certification.

Ice cubes at several restaurants were found to be dirtier than toilet water, Chinese media reported last week.

According to CCTV, ice cubes used by fast food giants including KFC, McDonald's and Guangzhou-based Kungfu at their Beijing branches were tested to contain bacteria at severe levels. The KFC ice cubes contained levels of bacteria which were 20 times higher than the national limit, and 13 times higher than water samples taken from toilet bowls.

"The market is in chaos," said an employee of an ice company, "Costs are increasing and those with qualification certificates would have closed down if they didn't rely on big buyers."