The U.S. Food and Drug Administration is launching a broader import control of all farm-raised catfish, bass, shrimp, dace (similar to carp), and eel from China, the agency said.

FDA said it will start to detain these products at the border until the shipments are proven to be free of residues from drugs that are not approved in the United States for use in farm-raised aquatic animals.

FDA says its action is designed to protect American consumers from unsafe residues that have been detected in these products. There have been no reports of illnesses to date.

We're taking this strong step because of current and continuing evidence that certain Chinese aquaculture products imported into the United States contain illegal substances that are not permitted in seafood sold in the United States, said Dr. David Acheson, FDA's assistant commissioner for food protection.

We will accept entries of these products from Chinese firms that demonstrate compliance with our requirements and safety standards.

During targeted sampling from October 2006 through May 2007, FDA repeatedly found that farm-raised seafood imported from China were contaminated with antimicrobial agents that are not approved for this use in the United States.

The contaminants were the antimicrobials nitrofuran, malachite green, gentian violet, and fluoroquinolone.

Nitrofuran, malachite green, and gentian violet have been shown to be carcinogenic with long-term exposure in lab animals. The use of fluoroquinolones in food animals may increase antibiotic resistance to this critically important class of antibiotics.

None of these substances is approved for use in farm-raised seafood in the United States, and the use of nitrofurans and malachite green in aquaculture is also prohibited by Chinese authorities. Chinese officials have acknowledged that fluoroquinolones are used in Chinese aquaculture and are permitted for use in China.

No Recall

The levels of the drug residues that have been found in seafood are very low, most often at or near the minimum level of detection.

FDA said it is not seeking recall of products already in U.S. commerce and is not advising consumers to destroy or return imported farm-raised seafood they may already have in their homes FDA is concerned about long term exposure as well as the possible development of antibiotic resistance.

The FDA action includes conditions under which an exporter can be exempted from FDA's detention action by providing specified information to the agency This information must demonstrate the exporter has implemented steps to ensure its products do not contain these substances and that preventive controls are in place. The additional import controls placed on seafood from China will last as long as needed, the agency said.

FDA said it may allow the entry into the United States and subsequent distribution into the marketplace of individual shipments of the Chinese farm-raised seafood products if the company provides documentation to confirm the products are free of residues of these drugs.

China says it has closed 180 food plants that were using industrial chemicals and additives in food products, acknowledging wide-ranging safety problems in its food supply.

But Chinese officials also reported seizing shipments of orange pulp and apricots shipped to China from the United States, claiming they contained excessive bacteria, mildew and sulfur dioxide.

The China Daily newspaper reported that most of the plants that were closed down were small, unlicensed operations, many with fewer than 10 employees. China has about 1 million food factories, most of them small.

It's the latest development in a string of food-safety problems including contaminated pet food and allegedly poisonous toothpaste being shipped to the U.S. and other North and South American countries.

In a spreading web of cross-border criticism, China is being blamed for shipping defective tires and lead-laden toys into the U.S.

The crackdown on food safety is being conducted by China's General Administration of Quality Supervision, Inspection and Quarantine. The agency said it has found 23,000 cases of infractions this year.

"These are not isolated cases," Han Yi, director of the administration's quality control and inspection department, said at a press conference, China Daily reported.

Investigators said they found food factories using such raw materials as dyes, mineral oils, paraffin wax, formaldehyde and the carcinogenic malachite green, in the production of flour, candy, pickles, biscuits, black fungus, melon seeds, bean curd and seafood.

Meanwhile, China turned the tables on the United States, seizing shipments of orange pulp and dried apricots that it said contained excessive bacteria, mildew and sulfur dioxide, according to Xinhuanet.

A statement carried on the website of the General Administration of Quality Supervision, Inspection and Quarantine said the orange pulp was supplied by Modern Skill Co., Ltd. and the dried apricots were supplied by Mariani Packing Company, Inc., CCTV reported.

The orange pulp was seized in east China's Shandong Province, while the dried apricots in Shenzhen, south China's Guangdong Province, the statement said.

The Chinese government said it has ordered local inspectors to intensify scrutiny over food products imported from the United States.