Customs officers seized more than 160 metric tons of smuggled bird nests worth about 2 billion yuan ($298.51 million) in a special operation.

The nests were estimated to have dodged taxes valued at more than 320 million yuan, according to a statement released by Shantou Customs in eastern Guangdong province on Friday.

The operation, codenamed 1901, was conducted by more than 200 customs and police officers comprising 45 small groups.

It was launched simultaneously in Shantou, Guangzhou and Shenzhen in Guangdong province, and Nanning and Pingxiang in Guangxi Zhuang autonomous region early Thursday morning after several months of investigation, the statement said.

A total of 18 suspects were detained after officers swooped on 25 warehouses, homes, and stores during the operation, the statement said.

“In addition to the large number of bird nests, many different kinds of certificates, documents, electronic evidence, bank books, and cash were seized,” said the statement.

A number of bank accounts involved in the case have been frozen for further investigation, the statement said.

Eight smuggling gangs once active in Guangdong and Fujian provinces and Guangxi Zhuang autonomous region have been busted following the crackdown.

A channel used to smuggle the nests from Southeast Asian nations to Guangxi via Vietnam before being transported to Guangdong and other coastal areas has been destroyed, the statement said.

Insiders said bird nests, which some consider to help maintain beauty and youth, can command high prices in the prosperous Guangdong and other coastal areas.