North Korea says it successfully conducted a ground jet test of a solid-fuel engine for a new-type of intermediate-range hypersonic missile.

The country's ruling Workers' Party newspaper, Rodong Sinmun, reported on Wednesday that the test was carried out at the Sohae Satellite Launching Ground in the northwest on Tuesday with leader Kim Jong Un attending.

Photos show flames coming from an engine's nozzle together with a large volume of white smoke. Those are typical characteristics of a solid-fuel engine, which enables a swifter missile launch than a liquid-fuel one.

The paper quoted Kim as saying the military strategic value of the weapon system is appreciated as important as ICBM, and that enemies know better about it.

The North carried out a ground jet test of a solid-fuel engine for a new-type intermediate-range ballistic missile in November last year. Two months later, it test-fired the missile.

Pyongyang has listed in its five-year plan through 2025 the completion of the development of warheads that can travel at a hypersonic speed of Mach 5 or more. It is accelerating efforts to develop a ballistic missile system that will supposedly make detection of signs for launch and interception more difficult.

Other countries are increasingly alarmed by the recent developments.