A foreign ministry statement on Thursday said "foreign minister of the DPRK Choe Son Hui will visit China from September 27 to 30" following an invitation from Beijing's top diplomat Wang Yi.

Earlier this month Kim told China's President Xi Jinping in Beijing that it was his "steadfast will" to "steadily develop" bilateral relations, according to a readout from North Korean state media.

Kim was on a rare foreign visit to China, his most important ally, joining Russia's Vladimir Putin alongside Xi at a massive military parade commemorating the 80th anniversary of the end of World War II.

The reclusive leader also affirmed the "friendly feelings" between the two countries, Pyongyang's Korean Central News Agency (KCNA) reported.

China's relationship with North Korea was forged in the bloodshed of the Korean War in the 1950s, and Beijing is a vital source of diplomatic, economic and political support for the isolated nuclear state.

But Pyongyang has been moving closer to Russia recently -- the two countries signed a mutual defence agreement last year, and North Korean soldiers are fighting in the Ukraine war.

Pyongyang will "invariably support and encourage the stand and efforts" of China to defend its sovereignty, territorial integrity and development interests, Kim said.

Xi told Kim the two countries should strengthen coordination on international affairs and "safeguard their common interests", according to Chinese state media.

Choe was seen alongside Kim in pictures released by KCNA ahead of his train ride from Pyongyang to Beijing, in which the North Korean leader was smoking a cigarette outside a carriage and grinning inside his lavish, wood-lined car in front of a national flag and emblem.