In recent years, there has been a string of major outbreaks of animal diseases worldwide, including China, such as foot-and-mouth disease, bird flu, and blue-ear disease, a highly pathogenic disease that can be fatal for pigs.

"No severe safety incidents have been registered for agricultural products supplied by the mainland to Hong Kong since the 1997 handover, due to the mainland's strict quality monitoring system," said Huang Guansheng, director of the department of supervision of animals and plants quarantine under the General Administration of Quality Supervision, Inspection and Quarantine.

The monitoring system, set up by the top quality watchdog, covers the whole food chain, tracing agricultural products from the field in the mainland to the table in Hong Kong, Huang said.

"The safety rate of the food supplied by the mainland to Hong Kong is now 99.999 percent, so high that few countries and regions in the world have it," York Chow, Hong Kong's food and health chief, was quoted by the Guangzhou Daily as saying on Sunday.

Analysts believe that the shrinking local agriculture sector in Hong Kong is the main factor behind the gradual increase of food supplies from the mainland in recent years.

Most meat and vegetables in Hong Kong come from the mainland, said Chow, without providing specific figures.

Live pigs, cattle, sheep, birds, aquatic animals and fruit are some of the major agricultural products imported from the mainland, according to the General Administration of Quality Supervision, Inspection and Quarantine.

"To ensure food safety, trade between the mainland and Hong Kong is only open to qualified suppliers registered with the administration," Huang said.

Since 2002, products exported to Hong Kong have been tested for about 44 varieties of banned and restricted drugs, as well as 47 kinds of toxic and harmful substances.

Yuen Cheung, president of the Hong Kong Imported Vegetables Wholesale Merchants Association, told China Central Television in January that vegetables from the mainland are abundant in quantity and cheap in price.

At the wet markets, retailers rarely state the origins of vegetables unless they were grown in Hong Kong. Local pork is so rare that consumers just assume that the pigs were imported from the mainland.

A Hong Kong resident surnamed Wong said that she doesn't care about the origin of the products and simply picks those with the best appearance.

"But it's true that mainland vegetables are cheaper than the local ones," she said.

"Also, I'm cautious about pesticide residue. I know they have quarantine inspections, but there is always the possibility that some things fall through the cracks," she said.

Authorities said that the future supply of agricultural products to Hong Kong might be endangered by the current shrinking profits for mainland suppliers.

"With the price of animal feed rising steadily in recent years, the livestock market in the mainland has seen constant high prices. But there are almost no increases in Hong Kong, which made many suppliers lose their interest," Huang said.

The administration has introduced a series of supportive measures to encourage suppliers trading with Hong Kong, he said.

Contact the writers at jinzhu@chinadaily.com.cn and kahon@chinadailyhk.com