Fines are being imposed on individuals attempting to bring bird's nest, a traditional delicacy, into the country as new regulations came into force on Thursday.
The delicacy, made from the saliva of a cave swift, has been added to the list of banned products, along with fresh fruit and vegetables.
Bird's nest is a popular gift in China, particularly in the south. However, only canned varieties are allowed past customs.
According to the rules approved by the General Administration of Quality Supervision, Inspection and Quarantine in August, people entering the country should also declare if their luggage contains genetically modified products, endangered animals or plants.
Those who fail to declare or provide false information face fines up to 5,000 yuan ($800).
Even if the goods are declared they must be accompanied by a valid certificate or else they will be destroyed.
Passenger numbers into and out of China are rising about 10 percent annually, and this increases the risk of foreign species threatening the domestic ecological system, the e-mail said.
People carrying endangered wild animals and plants out of the country also cause huge damage, it added.
Several people were stopped on Thursday as they attempted to bring in fruit at Guangzhou East Railway Station in Tianhe district where a service from Hong Kong terminates.
All the fruit was destroyed, said Chen Yan, a spokesman for Guangdong Entry-Exit Inspection and Quarantine Bureau.
Ports of entry across Shenzhen, also in Guangdong, confiscated 1 metric ton of banned items on Thursday, mostly seafood, meatballs, yogurt and fruit, according to the city's quarantine bureau.
"Bird's nest is one of the key targets because it can often carry the bird flu virus and some improperly processed bird's nest products also contain excessive nitrite that is harmful to humans," said Zhen Jianchuan, deputy director of animal quarantine for the bureau.
The canned bird's nest products are permitted as they are processed at temperatures high enough to kill most viruses, Zhen said.
He added that the authorities will make sure the new regulations are well publicized.
Liu Liping, from Guangzhou, said she was unhappy about the restrictions.
"We can buy bird's nest products from Southeast Asian countries and Hong Kong at much cheaper prices and the quality is better," she said. "The new rules only help protect domestic businesses and this is a profitable industry."
Meanwhile, the new quarantine regulations stipulate pet dogs and cats are allowed entry but there is a limit of one pet per person.
All quarantine and vaccination certificates are required.
Pets from areas that had rabies will be quarantined for 30 days. Others will be kept in quarantine stations for a week.
Mary Peng, co-founder of the International Center for Veterinary Services in Beijing, said the new regulations on pets are in line with measures taken in many countries.
"I bought cats in and out of China many times and I have witnessed China is becoming more humane, compassionate and caring in quarantining pets carried in by their owners from abroad," said Peng, a US citizen who has lived in China for more than two decades.
