North Korea test-fired one of its newest and most powerful missiles to boost its nuclear deterrent on Thursday, Kim Jong Un’s first weapons test since being accused of sending soldiers to Russia.

Tokyo said that the “ICBM-class” missile flew for longer than any other previously tested by the North, being airborne for about 86 minutes and hitting altitudes of 7,000 kilometres (4349 miles).

“We estimate that its flying altitude was the highest we have seen,” Japanese defence minister Gen Nakatani told reporters.

Seoul had warned a day earlier that the nuclear-armed North was preparing to test-fire another intercontinental ballistic missile or even conduct a nuclear test ahead of next week’s US elections.

The launch came just 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.

“The initial judgement so far is that (Pyongyang) may have test-fired a new solid-propelled long-range ballistic missile,” Seoul’s military said, adding the missile had flown around 1,000 kilometres (621 miles) after being fired on a lofted trajectory - meaning up, not out.