The Ministry of Agriculture and Rural Affairs said a slaughterhouse in the city of Hohhot reported the outbreak, adding that four pigs were infected with, and two had died from, African swine fever.
The world’s top pork producer has seen a steady stream of new outbreaks since the first case was reported in early August.
Authorities have banned the transport of live hogs and pig products from regions bordering provinces where African swine fever has been reported.
They have shut live markets and banned the use of feed derived from pig blood in order to contain the disease.
But a lack of manpower and financial resources at the local levels has hampered those efforts.
African swine fever is a devastating disease with no vaccine.
It can cause haemorrhaging in the skin and internal organs and death for swine in two to 10 days.
It is not harmful to humans.
It has many possible ways for transmission including direct contact between animals, animal feed and people travelling from one place to another.
The outbreak of the disease is not the first in Inner Mongolia.