A South Korean defence official told AFP that they "estimated that North Korea had fired an ICBM", without giving further details.

Seoul's Joint Chiefs of Staff earlier said it had detected the "launch of an unidentified ballistic missile in an eastward direction".

Tokyo also confirmed the launch, with Japan's defence ministry saying Pyongyang had fired "a suspected ballistic missile," as the coastguard warned ships not to approach fallen debris in the water.

The launch comes a day after North Korea fired a short-range ballistic missile as its minister of foreign affairs, Choe Son Hui, warned Pyongyang would take "fiercer" military action if the United States strengthened its "extended deterrence" commitment to regional allies.

Washington has been seeking to boost regional security cooperation and ramp up joint military drills in response to increasing provocations from the nuclear-armed North, which views all such moves as evidence of US aggression.

US President Joe Biden discussed North Korea's recent missile tests with Chinese counterpart Xi Jinping earlier this week and also spoke with leaders from Tokyo and Seoul, as fears grow that the reclusive regime will soon carry out its seventh nuclear test.

North Korea was also top of the agenda when leaders of China and Japan held their first face-to-face talks in three years Thursday on the sidelines of the Asia-Pacific Economic Cooperation (APEC) forum in Bangkok.

Experts said the launch of one of North Korea's most powerful weapons was a clear sign leader Kim Jong Un was displeased by the recent talks.

"Now, it's estimated to be an ICBM, if that's the case, it is a clear message to the US and Japan," said Han Kwon-hee, manager of the Missile Strategy Forum.

- Repeated launches -

Earlier this month, North Korea conducted a flurry of launches, including an intercontinental ballistic missile, which Seoul said at the time appeared to have failed.

Pyongyang also fired a short-range ballistic missile that crossed the de facto maritime border between the two countries and landed near the South's territorial waters for the first time since the end of the Korean War in 1953.

President Yoon said at the time that it was "effectively a territorial invasion".

Both launches were part of a November 2 barrage in which Pyongyang fired 23 missiles -- more than it launched during the whole of 2017, the year of "fire and fury" when Kim traded barbs with then US president Donald Trump on Twitter and in state media.

Experts say North Korea is seizing the opportunity to conduct banned missile tests, confident of escaping further UN sanctions due to Ukraine-linked gridlock at the United Nations.

China, Pyongyang's main diplomatic and economic ally, joined Russia in May in vetoing a US-led bid at the UN Security Council to tighten sanctions on North Korea.

Washington has responded to North Korea's sanction-busting missile tests by extending exercises with South Korea and deploying a strategic bomber.

Pyongyang has also been under a self-imposed coronavirus blockage since early 2020, which experts say would limit the impact of any additional external sanctions.