A senior official for food-export supervision has warned foreign businesses not to import illegally-exported products from China.

The warning follows recent reports of some poor-quality Chinese products entering foreign markets.

Li Yuanping, director general of the Bureau of Imports and Exports Food Safety, General Administration of Quality Supervision, Inspection and Quarantine (AQSIQ), said China imposes tight controls on food exports.

"No food products is allowed to be exported before passing a full range of checks by China Entry-Exit Inspection and Quarantine (CIQ) officials.

"And foreign importers need to especially make sure that the products they are buying are in compliance with all requirements," Li told China Daily.

More than 56 percent of all substandard food products imported by the US from China in April were "illegal products" that failed to meet US quality guidelines, according to the AQSIQ.

"It is these illegal products that have tarnished the reputation of all Chinese food products," Li said.

Li made the comments after returning from the United States where he had "effective communication" with his counterparts.

He said better cooperation mechanisms are needed between China, the US and other key import nations to weed out illegal players.

All legally exported Chinese food products should meet key requirements before being exported, he said.

Raw food producers must be registered with food safety authorities before being allowed to supply their products to food processors.

Food export companies have to be registered with AQSIQ, maintain high safety standards, and are subject to rigorous inspections by CIQ officials.

Exported food needs to be labeled according to the requirements of the importing countries and China.

Each batch of goods must pass official inspections before being sent abroad. Export certificates are given where needed.

But some importing countries, such as the US, do not require that the imported products come from officially-registered plants and accompanied by official certificates, which makes illegal imports possible, he said.