The African swine fever outbreak in Vietnam that has led to thousands of pigs being culled has spread to two more provinces in the country.

Multiple outbreaks were detected in the provinces of Hoa Binh and Dien Bien in the past two weeks, VN Express reported. Pigs in at least three villages in the two provinces were hit by the incurable disease.

Phung Duc Tien, the Deputy Minister of Agriculture and Rural Development, said the lack of a cure plus the diverse nature of the disease was fuelling its spread.

According to the Veterinary Department in the agriculture ministry, more than 6,400 pigs have been put down as of March 6. Tien added that local authorities should sanitize affected areas as well as control the movement of pigs to prevent the disease spreading.

The disease was first detected in early February in Hung Yen province. It has now spread to nine provinces and cities, including Hanoi.

Some places, including Taiwan, Dubai, the US and the United Kingdom, have banned pork imports from Vietnam because of the outbreak.

African swine fever is a viral disease that infects pigs via bodily fluids. There is no cure. However, the disease does not affect humans. So far 20 countries have reported outbreaks.