At least four North Korean troops have fled Kim Jong-un’s oppressive regime in the past seven months, and the antibodies indicate the solider was either vaccinated against the potentially deadly bacteria or had been exposed to it.
This comes just days after defence officials in Washington concluded the North is ploughing “hundreds of millions of dollars” into its nuclear, biological and chemical arsenal.
An intelligence official told South Korea’s Channel A: “Anthrax antibodies have been found in the North Korean defector who has escaped this year.”
However it is not known exactly which defector was found to be immune to the bacteria.
Senior defence analyst Shin Jong Woo, from the Korea Defence Security Forum, told the network a vaccine is likely to have been given to soldiers who handle the bacteria for military purposes.
Experts say North Korea has one of the largest stockpiles of chemical and biological weapons in the world.
Its sick arsenal is believed to include banned chemical agents such as VX and sarin, as well as diseases like plague, anthrax and smallpox.
Weaponised anthrax is likely to be inhaled by victims, and its initial cold-like symptoms quickly give way to severe breathing difficulties and shock, according to the World Health Organisation.
Infection can be treated using a vaccine, though its widespread use has not been approved because it has not been properly tested in humans.
However North Korea insists it is maintaining its commitments to international law, which bans the development, manufacture or stockpile of bioweapons.
In response to claims by the United States, the North vowed to “take revenge” for what it claimed were attempts by Donald Trump’s administration to further “stifle” the hermit kingdom.
Meanwhile, unconfirmed reports from Japanese media warned Kim’s regime is experimenting with ways to fit its long-range missiles with deadly pathogens, including anthrax.
The report in Japan’s Asahi newspaper warned the regime may have “already succeeded” in its initial tests.
The article cites an anonymous source connected to South Korean intelligence, and says: “North Korea has started experiments such as heat and pressure equipment to prevent anthrax from dying even at a high temperature of over 7,000 degrees generated at the time of ICBM’s re-entry into the atmosphere.
“In part, there is unconfirmed information that it has already succeeded in such experiments.”