ASF has been detected in areas more than 1,000 kilometres apart within the country, meaning it could spread further.
The FAO said there was no effective vaccine to protect swine from the disease, with outbreaks in its most virulent forms lethal in 100% of infected animals.
In efforts to control the spread of the disease, Chinese authorities have culled more than 24,000 pigs in four provinces.
China is a major pig-producing country and accounts for approximately half the global population of swine, estimated at 500 million.
The FAO also said that while this was not the first time African Swine Fever had been detected outside of Africa, its detection and diverse geographical spread in China has raised fears that the disease will move across borders to neighbouring countries of south-east Asia or the Korean peninsula, where trade and consumption of pork products is also high.
“The movement of pig products can spread diseases quickly and, as in this case of African Swine Fever, it’s likely that the movement of such products, rather than live pigs, has caused the spread of the virus to other parts of China,” said Juan Lubroth, the FAO’s chief veterinarian.
The FAO’s Emergency Centre for Transboundary Animal Diseases (ECTAD) is communicating closely with authorities in China to monitor and respond to the situation, as well as with authorities in neighbouring countries, to raise the importance of preparedness to respond to the threat of further spread.
However, the FAO has warned a complete restriction on the movement of animal and pork products could undermine efforts to stamp out ASF, as it could lead to illegal methods of transportation.
“Outbreaks such as this one are important reminders to us all that we must work together in a multilateral and inter-governmental effort to prevent and respond to outbreaks of animal diseases because these diseases know no borders,” said Kundhavi Kadiresan, FAO assistant director-general and regional representative for Asia and the Pacific.
“Good communication and coordination with the region’s private sector is essential to strengthen cooperation in ASF prevention and control,” she added.