A North Korean official rejected as "malicious slander" reports from South Korea's main intelligence agency that the North's autocratic leader, Kim Jong-un, executed 15 senior officials this year alone as he continued a reign of terror.

Seoul's National Intelligence Service reported during a closed-door briefing to lawmakers late last week that Kim does not tolerate different views and punished officials for challenging his authority, including executing a vice forest minister for raising complaints about his forestation policy.

On Thursday, CNN quoted Park Yong-chol, deputy director of the North's Institute for Research into National Reunification, as saying in an interview that the reports of executions are "malicious slander," accusing Seoul of trying to "link the allegations against to the august name of our Supreme Leader Marshall Kim Jong-un."

Park said, however, that the North carries out executions of "those who try to overthrow the government or subvert the system,"

claiming that it is "very normal for any country to go after hostile elements and punish them and execute them."

In late 2013, Kim demonstrated his brutality by executing his uncle Jang Song-thaek on charges of attempting to overthrow the communist regime, including contemplating a military-backed coup.

Park also rejected international criticism of the North's political prison camps, flatly denying such camps exist, even though there are "correction reform centers" for ordinary criminals.

Allegations of political prison camps in the North were cooked up by North Korean defectors, he said. (Yonhap)