North Korea earns nearly 1 trillion won ($863.9 million) every year from illegal activities in cyber space including the operation of gambling sites, a South Korean researcher said Thursday.

"Through operations in cyber gambling units, and development and sales of gambling programs, North Korea brings in an income of about 1 trillion won annually," Yoo Dong-ryol, the head of Korea Institute of Liberal Democracy said in a forum on cyber security hosted by the military's Defense Security Command.

The communist country's Reconnaissance General Bureau runs dozens of cyber bases in China and Southeast Asian countries as part of such broad efforts, he claimed.

The expert referred to the arrest by Cambodian police of 15 North Koreans in 2014 who were operating an illegal gambling site, as he made his case.

"At that time, the money confiscated by the Cambodian police amounted to some 10 billion won ... given this information and other intelligence, the amount North Korea earns from illegal cyber acts is estimated to be about 1 trillion won every year," according to the think tank head.

Under the Reconnaissance General Bureau and the United Front Department of the ruling party, North Korea maintains about 6,800 cyber troops who engage in cyber income earnings as well as cyber terrorism and online psychological warfare, he noted.

He added the ruling party department is currently conducting cyber operations against South Korea with around 160 propaganda websites and 1,000 SNS accounts that are used to disseminate rumors and criticism of the rival country. (Yonhap)