BEIJING - Beijing Tongrentang Co, a retailer of traditional Chinese medicine, has pulled all edible bird's nests off the shelf after excessive amounts of chemical nitrite were found in Malaysia-imported products in the East China's Zhejiang province.

The sales ban became effective at all Tongrentang stores in China and abroad on August 17, a day after State Administration for Industry and Commerce, the market watchdog, demanded retailers to tighten quality inspection of bird's nests, the company said in a statement Sunday.

"As a state company, Tongrentang will be responsible for the consumers, scrutinize all products and will not hesitate to destroy any bird's nests that fail to meet food safety standards," it said.

The company said consumers were welcome to lodge complaints to the headquarters if any of its stores were found to be selling bird's nests against the ban.

The industry and commerce administration in Zhejiang province said on August 15 that excessive amount of sodium nitrate was found in edible bird's nests imported from Malaysia.

Spot checks on the rare blood-red bird's 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 departments.

Sodium nitrate is a kind of chemical that is commonly used to produce food preservative and fertilizers.

Edible bird's nests, mostly made of the secretion from the salivary glands of birds, is an expensive delicacy and have been used in Chinese cooking for hundreds of years, and are traditionally believed to provide various health benefits.

In Hong Kong restaurants, a bowl of bird's nest soup can cost from $30 to $100.

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