The Ministry of Agriculture ordered its branches across the country to tighten their quality control procedures on animal feed and pigs on the wake of toxic pork cases in Shanghai, Xinhua news agency said today.

Some farmers are feeding their pigs with forages that contain clenobuterol hydrochloride, which makes the meat leaner and thus generates more profit, said the ministry in an urgent notice released last night.

The chemical has poisoned at least 336 people in Shanghai, which has negatively impacted the city's image, said the notice.

Symptoms of this type of food poisoning include dizziness, shaky hands and upset stomach, a previous report said.

Any illegal chemical producers or the merchants who use them will have their licenses revoked and they will be criminally charged, it said.

Agricultural authorities at all levels have to learn from this incident and enhance the administration and inspection of pork products to avoid further harms to public health, the ministry said.

However, most of China's pork products are safe to eat, an official from the ministry told Xinhua. "We should not mislead the public and increase their fear," Xinhua quoted the official as saying.

(Shanghai Daily September 21, 2006)