Wang Xiao, an officer from the Beijing Entry-Exit Inspection and Quarantine Bureau's animal and plant quarantine department, reminded buyers that as most mooncakes contain meat and eggs, they could conceivably transmit bird flu or foot-and-mouth disease.

"The sometimes-long mailing processes involved in ordering online mean the relatively short shelf life of mooncakes makes it difficult to ensure product quality," he said.

Retail industry sources have reported a surge in online purchases of mooncakes from outside the Chinese mainland in preparation for the festival, which falls on Sept 27 this year, when Chinese traditionally gather for family reunions.

A random search of overseas buying agents of exotic varieties of mooncakes, can yield as many as 10,000 results on Taobao.com, China's largest e-commerce platform.

Most of the mooncakes aimed at domestic consumers come from Vietnam, as well as Hong Kong and Taiwan.

The Beijing Morning Post reported on Sunday that numerous consumers had already experienced mooncake-delivery problem, with many orders intercepted by the authorities at quarantine checkpoints.