Seoul, South Korea - North Korean leader Kim Jong Un oversaw the ground test of an upgraded rocket engine, state media reported on Sunday, marking another key step in its weapons program.

Defense experts believe North Korea is planning to use its solid-fuel rocket engines for launching intercontinental ballistic missiles.

The engines enable faster missile launches as they require little preparation before ignition.

The latest test was "part of the national defense development plan in the period of the new five-year plan," Pyongyang's official Korean Central News Agency (KCNA) said, without elaborating on the date or location of the test.

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It was the first officially confirmed high-thrust solid-fuel engine test since September last year, when state media said an engine generated a maximum thrust of 1,971 kilonewtons.

KCNA reported the recent test had achieved a higher thrust of 2,500 kilonewtons.

The development demonstrates North Korea's "resolve to acquire missiles capable of hitting targets around the globe," Hong Min, an analyst at the Korea Institute for National Unification, told AFP.

"Given the increased maximum thrust, this indicates its intention to possess ICBMs with global strike range, as well as the ability to overwhelm missile defense systems," he added.

Photos released by KCNA showed leader Kim Jong Un inspecting what appeared to be part of the engine, flanked by officials.

Another image showed flames erupting from a ground-mounted engine, illuminating the surrounding test site in orange light.

Kim said that North Korea's defense capabilities had entered "a significant phase of change" in building up its strategic forces.