North Korea says it has carried out its first test of a nuclear weapon, the state news agency (KCNA) has reported.It said the underground test, carried out in defiance of international warnings, was a success and had not resulted in any leak of radiation.
The White House said South Korean and US intelligence had detected a seismic event at a suspected test site.
The White House said the reported test was a "provocative act", while China denounced it as "brazen".
In an unusually strong statement against its ally, China expressed its "resolute opposition" to the claimed test and said it "defied the universal opposition of international society".
Japan's Prime Minister Shinzo Abe, who is in Seoul for a meeting with South Korean President Roh Moo-hyun, said the test was "unpardonable".
Japanese Foreign Minister Taro Aso said Japan had detected seismic waves, but could not confirm whether they were from a nuclear test.
South Korea said it would "sternly respond".
President Roh has called an emergency meeting of South Korea's National Security Council and put the armed forces on a heightened state of alert.
Seoul also suspended a scheduled aid shipment to North Korea, the state news agency reported.
US White House spokesman Tony Snow said: "We expect the UN Security Council to take immediate actions to respond to this unprovoked act."
'Historic event'When it announced the test, KCNA described it as an "historic event that brought happiness to our military and people".
"The nuclear test will contribute to maintaining peace and stability in the Korean peninsula and surrounding region," KCNA said.
South Korea's Yonhap news agency reports that the test took place in Gilju in Hamgyong province at 1036 (0136 GMT).
The BBC's Jonathan Marcus says North Korea's claimed test does not necessarily mean it has a fully-fledged nuclear bomb or warhead that it can deliver to a target.
But the demonstration of North Korea's capability is what will shake-up the geo-politics of the region, he says.
Our correspondent says there will now be pressure on the UN Security Council to push for a resolution condemning North Korea and probably demanding a stiff menu of economic sanctions.
The Japanese and South Korean foreign ministers have held a telephone conference call with US Secretary of State Condoleezza Rice to discuss the issue, South Korea's foreign ministry said.
The BBC's Rupert Wingfield-Hayes in Beijing says China's statement is an indication of how strongly it is angered by North Korea's action, although Beijing will still be loath to support tougher sanctions against Pyongyang.
Reply
