China is preparing to establish a national standard for chemicals in edible bird nests after excessive amounts of nitrite were found in bird nests imported from Malaysia in August.

The Ministry of Health is collecting figures and doing research to set up a standard for chemical nitrite, Zhang Xudong, an official with the ministry's food safety and health standards department, said in an interview on Monday.

However, given the fact that bird nests are only consumed by a few people, China still lacks reliable figures and other evidence to map out a standard, Zhang said.

On Aug. 15, the industry and commerce administration of east China's Zhejiang province said that excessive amounts of sodium nitrate were found in edible bird nests imported from Malaysia.

Sodium nitrate is a type of chemical that is commonly used to produce food preservatives and fertilizers. Although it is widely used to cure meat, nitrite can cause health problems, including cancer, if ingested in large amounts.

Spot checks on rare "blood-red" bird nests from 491 dealers in Zhejiang found an average 4,400 mg of sodium nitrite per kg, far above the allowed cap of 70 mg per kg.

The Malaysian government later clarified that the problematic products were fake and were not endorsed by its food safety department.

Pharmacies on the Chinese mainland have taken edible bird nests off their shelves, while Hong Kong retailers have begun sales promotions to lure consumers.

Edible bird nests imported from Malaysia are rarely found in the Hong Kong market, with local retailers stating that most of their products are from Indonesia, another major bird nest exporter.

"The problematic blood-red bird nests from Malaysia have definitely dealt a heavy blow to the trade," said a wholesaler surnamed Fu from Hong Kong.

Edible bird nests, which are largely made out of secretions from the salivary glands of birds, are an expensive delicacy and have been used in Chinese cooking for hundreds of years. They are traditionally believed to provide various health benefits.

Previously, bird nests were mainly harvested from limestone caves. As the demand for the delicacy has increased, man-made nesting houses have been built to supplement natural sources.

Despite the fact that no academic studies have suggested any differences between the nutrition levels found in different bird' nests, the blood-red nests, referring to those harvested from caves, are much more popular than those harvested from nesting houses, which are usually white or light yellow in color.

Retailers dye the nests in different colors to woo consumers, as some diners believe the blood-red nests are more nutritious. Dyed bird nests often feature excessive nitrite levels.

In Hong Kong restaurants, a bowl of bird nest soup can cost anywhere from 30 to 100 U.S. dollars.

Malaysia is the world's biggest exporter of bird nests, with 95 percent of the nests sold to China.

In Malaysia, the amount of nitrite in unprocessed bird nests is capped at 70 mg per kg, while the amount in ready-to-eat nests is capped at 30 mg per kg.

China has no chemical standard for bird nests, but requires the amount of nitrite in 1 kg of smoked or cured meat to be equal to or less than 30 mg.