The disease has reached 24 provinces and regions since the first outbreak in August, roiling trade in the world's top pork market and related sectors. China slaughtered almost 700 million pigs in 2017.

African swine fever does not harm humans but is deadly to pigs and there is no vaccine or cure.

The rare update by the Ministry of Agriculture and Rural Affairs on the size of the culling follows growing attention to the issue from other markets.

Taiwan's President Tsai Ing-wen urged Beijing last month to "not conceal" information about the disease, after a dead pig was found on a beach on Taiwan's Kinmen island, which is about 10 km (6 miles) from the Chinese coastal city of Xiamen. The pig was later found to have the African swine fever virus.

"China has always followed the principles of 'being timely, open and transparent' when reporting the cases," said Guang Defu, a ministry spokesman, in the statement on its website.

In addition to the pigs culled on the infected farms, many more have been slaughtered by farmers seeking to exit the industry because of the impact the disease is having on prices and trade, said Pan Chenjun, a senior analyst at Rabobank.

Prices in some parts of the country have been sitting at loss-making levels for months, following restrictions on transport implemented after disease outbreaks.

"The numbers culled is just a small part," said Pan.

Liquidation by small farmers and the slow restocking and expansion of larger farms could reduce China's pig herd by about 20 percent in 2019, she said.

The effect of the swine fever outbreak is spilling over to animal feed markets. China's soymeal futures plunged almost 3 percent on Monday, following a fresh outbreak on a large breeding farm announced on Saturday.

By Hallie Gu and Dominique Patton, Reuters