Wearing a pink Korean dress and flashing a wide smile, television presenter Ri Chun Hee delivered the news of Pyongyang's sixth nuclear test with her usual gusto.

Using her trademark bombastic delivery, Ri announced on state television on Sunday the hydrogen bomb test was "a perfect success!" and a key step in "completing the state nuclear force."

The 74-year-old grandmother is considered a national hero who first took to the airwaves in 1971, leaving a career in acting for the broadcaster Korean Central Television (KCTV).