North Korea says it successfully tested a new intercontinental ballistic missile capable of hitting "anywhere in the world", under the supervision of leader Kim Jong-un.

Key points: Initial assessments said missile was "intermediate range", but North Korea says it was intercontinental

Initial assessments said missile was "intermediate range", but North Korea says it was intercontinental If proven intercontinental, would be North Korea's first

If proven intercontinental, would be North Korea's first Weapons analyst says missile could be powerful enough to reach Alaska

Weapons analyst says missile could be powerful enough to reach Alaska Australia has condemned the launch

The Hwasong-14 missile reached an altitude of 2,802 kilometres and hit its target precisely after flying for 933km in 39 minutes, the announcement on state television said.

"The test launch was conducted at the sharpest angle possible and did not have any negative effect on neighbouring countries," the statement said.

The launch is a potential game-changing development in North Korea's push to militarily challenge the United States, but a declaration that conflicts with earlier South Korean and US assessments that it had an intermediate range.

US, South Korean and Japanese officials said the missile was launched from an airfield in Panghyon, about 100km north-west of the North's capital, Pyongyang.

If confirmed, it would be North Korea's first intercontinental ballistic missile. ( Supplied: KCTV )

They earlier confirmed the missile flew for about 40 minutes and had "greatly exceeded" 2,500km in altitude — longer and higher than any other similar tests previously reported.

Those officials also said it covered a distance of about 930km before landing in Japan's Exclusive Economic Zone.

South Korean analysts said it was likely that it was a retest of one of two intermediate-range missiles launched earlier this year, which critics say were disguised tests of its long-range missile technology.

North Korea has conducted four missile tests since South Korean President Moon Jae-in took office in May, vowing to use dialogue as well as pressure to bring Pyongyang's nuclear and missile programs under control.

North Korean leader Kim Jong-un supervised the launch. ( Supplied: KCTV )

Long-range missile 'could reach Alaska'

The test still may be the North's most successful yet, with one weapons analyst saying the missile could be powerful enough to reach Alaska.

David Wright, co-director of the Global Security Program at the US-based Union of Concerned Scientists, said the assessments of the flight time and distance suggested the missile might have been launched on a "very highly lofted" trajectory of more than 2,800km.

The same missile could reach a maximum range of roughly 6,700km on a standard trajectory, Mr Wright said in a blog post.

"That range would not be enough to reach the lower 48 states or the large islands of Hawaii, but would allow it to reach all of Alaska," he said.

Soon after the launch, US President Donald Trump sent a tweet presumably referring to Mr Kim, that questioned whether "this guy [had] anything better to do with his life".

Mr Trump went on to suggest China could "perhaps" take action against North Korea "and end this nonsense once and for all!"

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White House officials said Mr Trump had been briefed on the launch, which took place hours before Independence Day celebrations in the United States. North Korea has previously fired missiles around this holiday.

The launch came just days before leaders from the Group of 20 (G20) nations were due to discuss steps to rein in Pyongyang's weapons program, which the North has pursued in defiance of UN Security Council and unilateral US and South Korean sanctions.

The White House said Mr Trump had brought up the North Korean missile program during a phone call with Chinese President Xi Jinping on Sunday (local time).

Chinese state media reported that Mr Xi warned Mr Trump that "some negative factors" were hurting US-China relations.

Officials said the missile was launched from Pangyhon, about 100 kilometres from the North Korean capital. ( Supplied: KCTV )

Australia, Japan, Russia condemn tests ahead of G20 meeting

Australia condemned the "provocative ballistic tests", which Foreign Minister Julie Bishop said were in breach of numerous United Nations Security Council resolutions.

"North Korea continues to threaten its neighbours while undermining regional and global security," Ms Bishop said in a statement.

"North Korea's long-term interests would be best served by ceasing its nuclear and missiles programs and focusing on improving the lives of its long suffering people."

China called for calm and restraint after the North's announcement, reiterating its opposition to ballistic missile testing.

Foreign Ministry spokesman Geng Shuang said UN Security Council resolutions had clear rules on North Korea's missile launches and China opposed it going against those rules.

Japanese Prime Minister Shinzo Abe also condemned North Korea's actions, saying he would work alongside world leaders to increase pressure on the regime.

"Japan will work to increase international pressure on North Korea by uniting strongly with the US and South Korea," Mr Abe said.

"I'm also planning to call on the Chinese President, Xi Jinping, and the Russian President, Vladimir Putin, to play a more constructive role."

Russian Deputy Foreign Minister Sergei Ryabkov called North Korea's test launch a breach of a UN Security Council resolution, the RIA news agency reported.

It also cited Mr Ryabkov as saying that tensions with Pyongyang risked leading to catastrophic developments and that the missile launch showed that the only way forward was to organise multilateral talks with North Korea.

The launch is the latest in a string of recent test-firings from North Korea. ( Reuters: Kim Hong-Ji )

ABC/wires