North Korea detonates nuclear bomb

Nuclear test: This black and white satellite image shows the site.
Explosion: A satellite image showing the site of a previous North Korean weapons test (AFP)

By North Asia correspondent Mark Willacy and wires

(ABC Australia) -North Korea's state media has confirmed the communist state has conducted a nuclear weapons test.

It is believed the blast was much stronger than Pyongyang's first test in 2006.

South Korea says weather agency officials detected what they called an artificial earthquake in the communist North this morning.

The government in Seoul immediately accused North Korea of conducting a nuclear weapons test.

Two hours later the secretive communist regime confirmed via its state media that it had detonated a nuclear device, saying the underground test was successful and was part of the country's nuclear deterrent policy.

In response, South Korean President Lee Myung-Bak called an emergency national security council meeting, while Japan's government said it had set up a crisis task force.

The Stalinist North last staged a nuclear test in October 2006 but it is believed this blast was much bigger.

Location unknown

The brief report by Pyongyang's official Korean Central News Agency (KCNA) gave no details of the location of the test.

However, South Korean officials said a tremor was detected around the north-eastern town of Kilju, near where the first test was conducted in October 2006.

"The Democratic People's Republic of Korea successfully conducted one more underground nuclear test on May 25 as part of the measures to bolster up its nuclear deterrent for self-defence in every way as requested by its scientists and technicians," the KCNA report said.

A spokesman for Japan's foreign ministry said it would respond to North Korea's nuclear test "in a responsible fashion" at the United Nations.

Meanwhile, a US State Department spokesman said the Obama administration was not able to confirm "at this time" that a nuclear test had been carried out.

Second test threat

The North had threatened a second test in protest at the UN Security Council's decision to censure its April 5 long-range rocket launch.

It announced it was quitting six-nation nuclear disarmament talks and would restart its plutonium-making program.

The communist state said the test had greatly inspired the army and people.

"The successful nuclear test is greatly inspiring the army and people of the DPRK all out in the 150-day campaign, intensifying the drive for effecting a new revolutionary surge to open the gate to a thriving nation," the KCNA report said.

"The test will contribute to defending the sovereignty of the country and the nation and socialism and ensuring peace and security on the Korean Peninsula and the region around it with the might of [the military first policy] Songun."

Tremor

The US Geological Survey said it detected what it called a 4.7-magnitude earthquake in North Korea.

The tremor struck at 9:54am (local time), 375 kilometres north-east of Pyongyang at a depth of just 10 kilometres, it said.

"Both South Korean and US intelligence authorities are analysing and closely monitoring the situation," a presidential spokesman in Seoul said.

The test was staged while South Korea was in mourning for former President Roh Moo-Hyun, who died Saturday after being questioned in a corruption probe.

North Korea carried out what it called a rocket launch on April 5, but the United States, South Korea and Japan said it staged a disguised ballistic missile test.

After the UN Security Council condemned the launch and tightened sanctions, the North vowed to conduct a second nuclear test as well as ballistic missile tests unless the UN apologised.

The United States has been involved in negotiations with the two Koreas, China, Japan and Russia aimed at scrapping North Korea's nuclear programme in exchange for energy aid under a landmark six-party agreement signed in 2007.

The negotiations deadlocked over a dispute with North Korea over how to verify disarmament, before taking a sharp turn for the worse with the long-range rocket launch.