Kim toured a munitions factory on Sunday and said "missile production capacity has rapidly been increased" in the country, an ally of Moscow.

During his visit Kim also ratified "three new long-term plans related to missile production capacity", the official Korean Central News Agency (KCNA) reported Monday.

Pyongyang has sent missiles and other weapons to Russia for its war in Ukraine, along with thousands of troops, according to South Korean and Western intelligence agencies.

China, meanwhile, has historically been the biggest diplomatic, economic and political backer of North Korea, which remains under crippling international sanctions.

Kim's factory tour came ahead of his journey to Beijing, where he will join leaders including Russian President Vladimir Putin at a military parade in the Chinese capital.

"By stressing advances in missile production, Pyongyang aimed to project deterrent power against Washington and Seoul, and to signal that it is on track to meet its five-year missile production goals," Lim Eul-chul, a professor at the Institute for Far Eastern Studies at Kyungnam University, told AFP.

The Beijing event, which will commemorate 80 years since the end of World War II, is regarded by many as the North Korean leader's first multilateral international gathering.