The launch was North Korea's first weapons test since being accused of sending soldiers to Russia.

South Korea's military said its "initial judgement" was that the projectile may have been a "new solid-propelled long-range ballistic missile".

Beijing's foreign ministry said Thursday that it was "concerned about developments on the (Korean) peninsula."

"China... has consistently maintained that preserving peace and stability on the peninsula and promoting the process of political resolution to the peninsula issue aligns with the common interests of all parties," ministry spokesman Lin Jian said.

"We hope all parties will make efforts toward this goal," he told a regular press briefing in Beijing.

The launch came hours after US and South Korean defence chiefs called on Pyongyang to withdraw its troops from Russia, warning that North Korean soldiers in Russian uniforms were being deployed for possible action against Ukraine.

China is a longtime socialist ally of North Korea, which relies heavily on Beijing for diplomatic and economic support.

Beijing and Seoul are also major trade partners.