North Korea said Wednesday it has successfully conducted the final test-firing of a new hypersonic missile a day earlier, as it continues to develop new weapons systems amid stalled nuclear negotiations with the United States.

On Tuesday, South Korea's defense ministry said the North fired what appeared to be a ballistic missile into the East Sea which flew over 700 kilometers at a maximum altitude of 60 km and a top speed of Mach 10, or 10 times the speed of sound.

"The test-fire was aimed at the final verification of overall technical specifications of the developed hypersonic weapon system," the Korean Central News Agency (KCNA) said.

North Korean leader Kim Jong-un attended the firing.

During Tuesday's test, the hypersonic glide vehicle demonstrated "glide jump flight," "corkscrew maneuvering," and hit "the set target in waters 1,000 km off."

"The superior maneuverability of the hypersonic glide vehicle was more strikingly verified through the final test-fire," the KCNA said.Kim expressed "great expectations" that the officials in the missile research sector would "help bolster the war deterrent of the country with their continued ultra-modern scientific research achievements."

The latest firing marked the North's second missile launch in less than a week.

South Korea's Joint Chiefs of Staff earlier downplayed the North's hypersonic missile claims as "exaggeration," but said the latest launch demonstrated "improvement" from the previously tested versions.

The North conducted the first test-firing of what it claimed to be a "hypersonic" missile Hwasong-8 in last September, though the missile flew at a speed of around Mach 3 at that time.

Developing a hypersonic weapon was one of the North's "five core tasks" under a five-year plan to strengthen its defense capabilities unveiled at its eighth party congress held a year ago.

On Tuesday, Kim again stressed "the need to further accelerate the efforts to steadily build up the country's strategic military muscle both in quality and quantity."

The North's latest saber-rattling came as nuclear negotiations between Washington and Pyongyang remain stalled since the no-deal Hanoi summit in February 2019.

President Moon Jae-in expressed concern over North Korea's repeated missile launches ahead of South Korea's presidential election in March, and ordered officials to come up with measures to ensure "no further tension in inter-Korean relations."

The White House also condemned North Korea's latest launch and urged the North to engage in dialogue. (Yonhap)