South Korea confirmed its seventh case of African swine fever today (26 September), just over a week after the virus was first detected and prompted authorities to step up disinfection measures.

The source of the outbreak has not been confirmed, but the virus has been found on hog farms near the border with North Korea, which reported an outbreak in May.

Troops and equipment normally used to guard against North Korean provocations were deployed this summer to monitor and trap wild boars suspected of carrying the virus, a South Korean military official told Reuters.

"We can't shoot them because it would be a violation of the armistice agreement," the official said, referring to the 1953 pact with the North that halted fighting but did not end the war and has governed the border ever since.

The border decades after the 1950-53 Korean War is laced with landmines, razor wire, and high-tech surveillance equipment. The 250-km (155-mile) DMZ is also home to wild animals that thrive in the wooded no-man's land.

The animals may be deterred by fences and other barriers along the DMZ, the military official added.

The US-led United Nations Command (UNC), which helps oversee the DMZ, is not involved in containing the virus, the official said. The UNC did not respond to a request for comment.

The efforts against the highly contagious disease, which is fatal to pigs but does not affect humans, have taken on new urgency as more cases are reported.

The wild boars trapped by the military have tested negative for African swine fever, the military official said. Two boars found dead in the DMZ had also tested negative, the defence ministry said.

South Korea has deployed 1,173 military personnel and 166 decontamination vehicles to seven areas, deputy defence ministry spokesman Roh Jae-cheon said on Thursday.

"There have been no cases of wild boars crossing the border from North to South within the DMZ," he told a news briefing. "No attempt was made to enter general outposts and no boars have been shot dead inside the DMZ."

More than 300 South Korean soldiers and 40 decontamination trucks were deployed along roads and checkpoints near the border on Thursday to control the spread of the virus, Roh said.

South Korea has been disinfecting people, cars and equipment at a liaison office jointly run with the North in the border city of Kaesong, said an official at the Unification Ministry, which handles cross-border ties.

DMZ "peace trails" used by hikers have also been closed.