China on Tuesday reported the third outbreak of African swine fever in Guangdong, the southern province that borders Hong Kong, in less than a week.
In the latest incident, in Boluo county, Huizhou, 11 of 90 pigs on a farm were killed by the deadly disease, the agriculture ministry said.
On Saturday, similar infections were found in 30 pigs on a farm of more than 6,000 in the Huangpu district of Guangzhou. Nine of the animals have since died of the illness.
Local authorities responded by sealing off the area and slaughtering 6,027 hogs.
The outbreak in Guangzhou came after a farm in nearby Zhuhai reported the virus on Thursday. Authorities there slaughtered 1,598 pigs as a precautionary measure.
The three cases were the first in Guangdong, and prompted authorities in Hong Kong to increase their efforts to prevent meat being smuggled into the city.
Eleven animals that had contracted the disease died at a slaughterhouse in the Xiangzhou district of Zhuhai, China News Service reported earlier.
China has reported at least 92 outbreaks of African swine fever since the virus was first detected in northeast Liaoning province in early August.
The cases, in 23 provinces and regions, have resulted in the slaughter of more than 630,000 pigs, according to the state news agency China News Service.
Meanwhile, China has detected the African swine fever virus in some protein powders made using pork blood and manufactured by a Tianjin-based company, the General Administration of Customs said in a statement on Tuesday.
The raw material for the 73.93 tonnes of contaminated protein products, mainly used in animal feed, came from 12 slaughter houses in Tianjin, the administration said.
The case comes despite China in September banning the use of food waste and pig blood as a raw material in the production of feed for pigs, in a bid to halt the spread of the disease.
The protein products were made by a subsidiary of Tianjin Baodi Agri & Tech Co Ltd, which has operations running from hog breeding and cooked meat production to biochemical production.
Additional reporting by Reuters