There is no vaccine for the highly contagious disease fatal to pigs, but which does not affect humans. It spread rapidly across China after being detected there last August, and has also been reported in Vietnam.

According to the latest Reuters report, the North's outbreak was confirmed on Saturday (25 May) at a farm in its province of Jagang near the border with China, South Korea's agriculture ministry said in a statement, with more than 20 hogs culled and more than 70 dead from the virus.

"There is a possibility that the virus could spread to the South and we plan to carry out extra disinfection measures," Oh Soon-min, the ministry's director general, told a news briefing after a government meeting on ways to block the virus.

Measures will include stepping up disinfection in areas near the shared border, the ministry said.

South Korea's unification ministry said it would make use of a liaison office with its reclusive neighbour to work out detailed protection measures with the North.

Pork, cheaper than beef, is a popular meat in South Korea, which had about 11.2 million pigs in the first quarter, data from Statistics Korea shows.

North Korea has not confirmed the swine fever outbreak, but the state-run Rodong Sinmun newspaper on Friday (31 May) carried three articles on the risks posed by the virus and its rapid spread.

However, South Korea's agriculture ministry said its neighbour had reported the outbreak to the Paris-based World Organisation for Animal Health (OIE) on Thursday (30 May), and took steps to control its spread, including disinfection.

Lack of prevention capability

The North's outbreak comes as it grapples with food shortages, when four in ten citizens are going hungry after the worst harvest in a decade, the United Nations said this month.

"The food and nutrition insecurity situation in North Korea is worrying and the African swine fever outbreak puts additional pressure on the availability of proteins of animal origin," said Vincent Martin, an official of the UN's Food and Agriculture Organisation in China and North Korea.

The North's pork consumption has increased recently as leader Kim Jong Un pushed to increase meat supply, said Kwon Tae-jin of the GSnJ Institute, an expert on its agriculture.

"It will mainly affect the elite because not every North Korean can easily eat pork or other types of meat," he said, referring to the virus outbreak.

"The biggest concern is lack of sanitary and prevention capability."

North Korea raises mainly chicken, ducks and rabbits, but its pig population in 2017 rose 8.9 percent to 2.6 million, according to Statistics Korea.

South Korean pork producers worry that wild boars near the border could carry in the virus, hitting pig farms.

"Prevention is the best way to counter the virus," said Oh Yu-hwan, an official of the Korea Pork Producers' Association.

"The government should step up controlling wild boars, otherwise it could threaten the foundation of the industry."

The government plans to build more fences to protect farm animals from wild boars and relax rules on hunting them, the ministry said.

However, the average retail price of pork belly changed little in South Korea, standing at 1,857 won ($1.56) per 100 gram (0.22 lb) on May 30 from 1,854 won a year earlier, data from state-run Korea Agro-Fisheries & Food Trade Corp shows.

Shares of South Korean animal medicine suppliers, Eagle Veterinary Technology and Cheil Bio rallied as much as 23 percent and 16 percent, respectively, while those of animal feed maker Woosung Feed jumped more than 12 percent.

($1=1,191.3000 won)