South Korea's media regulator said on Monday it was banning access to a North Korean propaganda music video that it said idolised and glorified leader Kim Jong Un as a "friendly father" and "great leader."

South Korea's National Security Act blocks access to the North's government websites and media to restrict exposure to the efforts by Kim's autocratic regime to "praise, incite or propagate" its activities.

The two Koreas are still technically at war since an armistice ended the 1950-1953 Korean War, not a peace treaty.

The decision to ban the video was made after intelligence authorities asked for a review on whether it breached the law, Seoul's Korea Communications Standards Commission.

"The video is typical content linked to psychological warfare against South Korea, as it was posted on a channel operated to connect with the outside world and mainly focused on unilaterally idolising and glorifying Kim," the regulator said in a statement.

The video has become an unlikely social media hit around the world, going viral on short-form video app TikTok and other platforms.

Pyongyang's state media often displays exaggerated demonstrations of loyalty by citizens toward its leaders to help the latter consolidate power and to craft a personality cult around them.

Titled "Friendly Father," the clip was unveiled last month by the North's state television. It shows North Koreans ranging from soldiers to school children exuberantly belting out such lines as: "Let's sing, Kim Jong Un the great leader" and "Let's brag about Kim Jong Un, a friendly father."

The South's regulator blocked access to some North Korean propaganda YouTube channels last year on the spy agency's request. (Reuters)