A new regulation by the State agriculture ministry will forbid the treating of tuna with carbon monoxide. The regulation will come into force May 1 this year.

According to a report in the Guangzhou Daily, tuna retains its color and taste only when kept in temperatures below minus 60 degrees Celsius. But not all sellers can afford to do so.

"In Guangzhou, Shanghai and some other regions, 70 percent to 80 percent of tuna is treated with carbon monoxide," said Huang Baoshan, an official with China Fishery Association, who added that even some luxury hotels and big supermarkets sold carbon-monoxide-treated tuna.

According to experts, rotten food causes acute intestinal disease and may be harmful to the kidney. Poisoning caused by carbon-monoxide-treated tuna has been reported in Japan and the United States previously.

The newspaper said most of the carbon-monoxide-treated tuna comes from foreign countries.

However, a number of storehouses with very low temperatures have been built recently by domestic companies.

Editor: Yan