In a statement published on state media, North Korea said a rocket carrying the spy satellite crashed into waters off the Korean Peninsula's western coast after it lost thrust following the separation of its first and second stages.

It said scientists were examining the cause of the failure.

South Korea's military earlier said the North Korean rocket had "an abnormal flight" before it fell in the waters.

North Korea launched a rocket Wednesday, South Korea and Japan said, prompting brief evacuations in those countries as the North appeared to be attempting to put its first military spy satellite into orbit.

The rocket was launched about 6.30 am from the North's northwestern Tongchang-ri area, where the country's main space launch centre is located, the Joint Chiefs of Staff said in a statement.

South Korea's military was trying to confirm whether the launch was successful, according to the statement, which also noted that South Korea has bolstered its military readiness in close coordination with the United States.

Following the launch, the South Korean capital of Seoul issued alerts over public speakers and cellphone text messages telling residents to prepare for evacuation. But there were no reports of damages or major disruption and Seoul later lifted the alert.?

The Japanese government activated a missile warning system for its Okinawa prefecture in southwestern Japan, believed to be in the path of the rocket.

"Please evacuate into buildings or underground," the alert said. Authorities later lifted the calls for evacuation.

Japan's coast guard said Monday that North Korea informed it of a plan to launch a satellite between May 31 and June 11. Japan's defense minister had ordered its forces to shoot down the satellite or debris, if any entered Japanese territory.

A satellite launch by North Korea is a violation of UN Security Council resolutions that ban the country from using ballistic technology because it's regarded as a cover for missile tests.

Ri Pyong Chol, a top North Korean official and close associate of leader Kim Jong Un, had said on Tuesday that North Korea was compelled to secure "a reliable reconnaissance and information" system because of what it said were escalating security threats by the United States and its allies. He said the North would launch a spy satellite in June.

It wasn't immediately clear whether a North Korean spy satellite would significantly bolster its defences. The satellite disclosed in the country's state-run media didn't appear to be sophisticated enough to produce high-resolution imagery. But some experts note that it is still likely capable of detecting troop movements and big targets, such as warships and warplanes.

Recent commercial satellite imagery of the North's main rocket launch center in the northwest showed active construction activities indicating that North Korea plans to launch more than one satellite, however.?

And in his statement Tuesday, Ri said the country it would be testing “various reconnaissance means."

He said those surveillance assets are tasked with “tracking, monitoring, discriminating, controlling" and responding, both in advance and real time, to moves by the United States and its allies.

With three to five spy satellites, North Korea could build a space-based surveillance system that allows it to monitor the Korean Peninsula in near real-time, according to Lee Choon Geun, an honorary research fellow at South Korea's Science and Technology Policy Institute.

During his visit to the country's aerospace agency earlier this month, Kim emphasized the strategic significance a spy satellite could have in North Korea's standoff with the United States and South Korea.

The satellite is one several high-tech weapons systems that Kim has publicly vowed to introduce in recent years. Other weapons he has pledged to develop include a multi-warhead missile, a nuclear submarine, a solid-propellant intercontinental ballistic missile and a hypersonic missile.

Denuclearization talks with the US have been stalled since early 2019. In the meantime, Kim has focused on expanding his nuclear and missile arsenals in what experts say is an attempt to wrest concessions from Washington and Seoul. Since the beginning of 2022, North Korea has conducted more than 100 missile tests, many of them involving nuclear-capable weapons targeting the US mainland, South Korea and Japan.

North Korea says its testing activities are self-defense measures meant to respond to expanded military drills between Washington and Seoul that it views as invasion rehearsals. US and South Korean officials say their drills are defensive and they've bolstered them to cope with growing nuclear threats by North Korea.

The UN imposed economic sanctions on North Korea over its previous satellite launches, which it views as covers for testing its long-range missiles. China and Russia, permanent members of the UN council who are now locked in confrontations with the US, already blocked attempts to toughen sanctions over Pyongyang's recent ballistic missile tests.

Before Tuesday's launch, both South Korea and Japan said such a move would undermine regional peace. The South Korean Foreign Ministry warned that North Korea would face consequences.

After repeated failures, North Korea successfully put its first satellite into orbit in 2012, and the second one in 2016. The government said both are Earth-observation satellites launched under its peaceful space development programme, but many foreign experts believed both were developed to spy on rivals.