China appeared to go on the defensive Friday in response to rising concern about the safety of its food and drug exports, asking the United States to clarify its regulations on the use of antibiotics that turned up in Chinese catfish in Alabama and two other southern states.

In a notice on its Web site, the General Administration of Quality Supervision, Inspection and Quarantine, China’s main food safety regulator, said it had contacted its American counterpart about the use of fluoroquinolones.

In its statement, the quality inspection administration asked Washington to “deal with the problem in an objective, scientific and equitable way.”

It also warned that the U.S. should not violate World Trade Organization’s rules, which give countries the right to ensure food safety for consumers but not to manipulate health standards to protect domestic producers.

The Food and Drug Administration has not responded, the Chinese regulator said.

Mississippi, Alabama and Louisiana recently banned catfish from China after tests found traces of ciprofloxacin and enrofloxacin, both in the fluoroquinolone family. The antibiotics are used to treat tuberculosis, pneumonia and other illnesses in people and prevent infections in animals.

The Chinese regulator said the drugs are allowed in China, the EU and Japan and said the FDA allows their use if below concentration levels of five parts per billion.

Officials from the Chinese agency refused to comment further on their statement, which mentioned only Mississippi and Alabama.

Alabama Agriculture Commissioner Ron Sparks in Montgomery said it’s “pretty obvious what we’ve done. Alabama opened doors to clarification of what FDA policies are.”

“I’m just glad that it’s on the table, that there can be some dialogue,” Sparks said Friday. “I just think it’s time we take this food safety issue seriously.”

According to the FDA, fluoroquinolones have never been approved for use in aquaculture and any amount detected in fish tissue deems the product adulterated. Regulations against the antibiotics in food are intended to prevent bacteria from developing resistance to the drugs.

China is worried about the damage to consumer confidence in its products by a series of scandals involving tainted Chinese exports. Many of the tainted goods are produced by farmers and small factories, and a ban on their trade by importing nations would threaten jobs in a largely rural country with already high unemployment.

On Thursday, U.S. officials asked their Chinese counterparts to increase oversight of food and drug exports. The FDA also said it was stopping all imports of Chinese toothpaste to test for a deadly chemical reportedly found in tubes sold in Australia, the Dominican Republic and Panama.

The FDA also warned consumers not to buy or eat imported fish from China labeled as monkfish because it might actually be pufferfish, which contains a potentially deadly toxin called tetrodotoxin. Eating pufferfish that contains the potent toxin could result in serious illness or death, the FDA said.

Dozens of people have died in Panama after taking medicine contaminated with a chemical traced to a Chinese company. China also was the source of the toxic chemical in pet food that has killed an unknown number dogs and cats in the United States.

China’s former top drug regulator went on trial earlier this month accused of taking bribes to approve untested medicine, including an antibiotic that killed at least 10 patients last year before it was taken off the market.

The Chinese leadership has pledged to strengthen its safety controls.

“The Chinese government attaches great importance to food and drug safety. We are making efforts to improve the monitoring system of the safety of food and drug,” Chinese Foreign Ministry spokeswoman Jiang Yu said at a regular briefing Thursday.