BEIJING - China, the world's largest producer of pork, is battling an African swine fever outbreak that could potentially devastate herds.

Authorities say the disease, which only affects pigs and wild boar, has been detected in multiple locations across the vast country. It's unclear exactly how many pigs have died or been culled.

The disease comes as China seeks to shift pig rearing from farmyards to vast breeding operations where waste and the spread of disease can be better controlled.

China produces hundreds of millions of pigs annually and pork is a staple of the Chinese diet, accounting for more than 60 per cent of animal protein consumed.

The fluctuating price of pork is highly sensitive and the government maintains a large frozen supply to release when rise too high.