Vietnamese authorities have traced an outbreak of hoof-and-mouth disease among cattle in northern Yen Bai province to 120 infected buffalo that were donated to poor farmers, an animal health official said Monday.

Hoof-and-mouth disease has broken out in six provinces across north-central Vietnam in the aftermath of massive floods in early November that compromised hygiene on farms.

In Yen Bai, according to Hoang Van Nam of Vietnam's Department of Animal Health, the local officials had commissioned a separate company to buy 120 buffalo as charitable donations for poor farmers. But the company bought infected animals, which spread the disease to the farmers' other cattle.

"The danger of infection spreading to other localities is very high," Nam said.

Yen Bai has reported over 250 animals infected, and the provinces of Nghe An and Ninh Binh were also reportedly hard hit.

Nam said animal health animal officials were intensifying control over cattle transport in affected areas, and vaccinating healthy animals.

Hoof-and-mouth disease is a viral illness which infects and sometimes kills cattle, pigs, buffalo and other hoofed animals. Outbreaks in Europe and China have led to large-scale culling of animals.