, SEOUL, May 25 – North Korea said it had carried out a second and more powerful nuclear test, despite international pressure to rein in its nuclear programmes after years of disarmament talks.
The communist state, which stunned the world by testing an atomic bomb for the first time in October 2006, had threatened another test after the UN Security Council censured it following a long-range rocket launch in April.
The North "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," the official Korean Central News Agency (KCNA) said.
"The current nuclear test was safely conducted on a new higher level in terms of its explosive power and technology," it said.
Across the border in South Korea, President Lee Myung-Bak convened an emergency National Security Council meeting for later in the day, and both South Korea and Japan announced the formation of government crisis teams.
Japan said it may try to get the UN Security Council to meet over the nuclear test.
The KCNA report gave no details of the location of the test. But South Korean officials said a tremor was detected around the northeastern town of Kilju, near where the first test was conducted in October 2006.
The US Geological Survey said it detected a 4.7-magnitude earthquake in North Korea, which it said struck 375 kilometres (230 miles) northeast of Pyongyang — also around the same region as the North’s first atomic test.
In the United States , a State Department spokesman said the US was not able to confirm "at this time" that a nuclear test had been carried out.
Five nations – China, Japan, Russia, South Korea and the United States – have been involved in long-running talks intended to get the secretive North to abandon its nuclear programmes in exchange for energy and security guarantees.
The intermittent talks have repeatedly seen apparent breakthroughs turn back to stalemate. The six-party negotiations led to an agreement signed in 2007 under which the North said it would dismantle its nuclear facilities.
But the North irked the international community with a long-range rocket launch in April this year, a move that many nations said was actually a ballistic missile test.
After the 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.
It had also announced it was quitting the six-way talks, which are hosted by its closest ally China, and said it would restart its plutonium-making programme.
In its report, KCNA said the results of Monday’s nuclear test had resolved "scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology."
North Korea has frequently said it needs a nuclear deterrent to prevent any attack, and Monday’s report echoed those words, using the official term "Songun" — or the country’s army-first policy.
It said the nuclear test would "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 Songun."
Monday’s test was staged while South Korea was in mourning for former president Roh Moo-Hyun, who leapt to his death Saturday after being questioned in a corruption probe.