The US has said it will halt imports of five types of farmed Chinese seafood, because they contain antibiotics that are not allowed in North America. The US FDA said it would detain shipments of catfish, basa, shrimp, dace and eel.

China has countered saying, that its exports were no threat to health and "guaranteed" the safety of its products.

The FDA said it was not issuing a recall of seafood already on US store shelves as the drug levels were not dangerous but only slightly above detectable levels.

This is the latest in a number of US warnings about Chinese products; in past weeks there have been concerns about contaminated toothpaste, tyres, dog food and paint used in toy trains.

The FDA said it had found that Chinese seafood tested between October 2006 and May 2007 to be repeatedly contaminated with ant microbial agents. Some of the substances included nitrofuran, malachite green and fluoroquinolone, which, according to the FDA, may help build up a resistance to antibiotics when used in food animals.

"We''re taking this strong step because of current and continuing evidence that certain Chinese aquaculture products imported into the US contain illegal substances that are not permitted in seafood sold in the US," the it said.

The agency said that it would accept entries of those products from Chinese firms that demonstrate compliance with "our requirements and safety standards."