According to a statement from the Chinese Foreign Ministry, the Chinese government is resolutely opposed to the DPRK's "flagrant conducting" of the nuclear test as it ignored the universal opposition among the international community.

China strongly demanded the DPRK live up to its commitment to non-nuclearization of the Korean Peninsula, stop any activity that might worsen the situation and return to the six-party talks, said the statement.

It calls for a calm response from all parties concerned and urges them to stick to peaceful resolution of the issue through consultations and dialogues.

The nuclear test, the first of its kind conducted by the DPRK, came about a week after the country announced it would carry out an unprecedented atomic test under safe conditions. The official Korean Central News Agency (KCNA) ruled out any danger of radioactive emissions during the course of the test, and the DPRK Foreign Ministry said it would never use nuclear weapons first.

In a statement on Monday, U.S. President George W. Bush said the United States condemned the claimed nuclear test and demanded immediate U.N. Security Council action.

"Such a claim itself constitutes a threat to international peace and security. The United States condemns this provocative act," he said.

"We reaffirm our commitment to a nuclear-free Korean peninsula, and all of us agree that the proclaimed actions taken by North Korea (DPRK) are unacceptable and deserve an immediate response byte United Nations Security Council," the US president said after conversations with leaders of China, South Korea, Russia and Japan.

Bush also warned the DPRK not to spread nuclear weapons or material to other countries.

Earlier on Monday, the White House said a nuclear test by the DPRK would be a provocative act, in defiance of the will of the international community and of the call to refrain from actions that would aggravate tensions in North East Asia.

Bush telephoned Russian President Vladimir Putin to discuss the crisis sparked by the nuclear test.

"The presidents agree that the brazen act of the DPRK has dealt a blow to the nonproliferation regime and with this in mind they stress the need for coordinated actions to resolve the problem," the Kremlin said in a statement.

In Moscow, Russia on Monday condemned the nuclear test, saying it had caused huge damage to the process of nuclear nonproliferation.

"Russia definitely condemns the nuclear test by the DPRK" and the move "has caused huge damage to the process of nuclear nonproliferation," Putin was quoted by the Itar-Tass news agency as saying.

Putin told the Russian envoy to hold consultations on the test with the UN Security Council.

"I hope North Korea (DPRK) will return to the process of negotiations," he said.

Mikhail Kamynin, spokesman for the Russian Foreign Ministry, said that Russia was imperatively calling on the DPRK "to take steps, without further delay, to go back to the regime of the Nuclear Weapons Nonproliferation Treaty and to resume the six-nation negotiations."

Russia is now examining the ecological system in the region bordering the DPRK.

Meanwhile, U.N. Secretary-General Kofi Annan expressed deep concern over the nuclear test, and urged all parties to respond to this grave challenge in a constructive manner.

"This action violates international norms of disarmament and nonproliferation, as well as the current international moratorium on nuclear testing. It aggravates regional tensions in and around the Korean Peninsula, and jeopardizes security both in the region and beyond," he said in a statement.

British Prime Minister Tony Blair defined Pyongyang's nuclear test as an "irresponsible act," saying the move shows the DPRK's disregard for the concerns of its neighbors and the wider international community and contravenes its commitments under the Non-Proliferation Treaty and U.N. Security Council Resolution 1695.

According to Japanese Chief Cabinet Secretary Yasuhisa Shiozaki, Japan and the United States have decided to refer the reported nuclear test to the UN Security Council. Japan would follow the grave situation with great intensity.

South Korean Prime Minister Han Myeong-sook and Japanese Prime Minister Shinzo Abe on Monday discussed DPRK's nuclear test and urged calmness in dealing with the nuclear issue.

Abe said the DPRK's nuclear test "will never be pardonable" and it is necessary to collect and analyze more intelligence on the situation with a calm head.

Han said the nuclear test had shattered the expectations of the South Korean people and the international community to resolve the nuclear issue on the Korean Peninsula in a peaceful and diplomatic way, and had breached the Joint Statement adopted during the 4th round of the six-party talks on Sept. 19 last year.

The European Union (EU)'s current presidency holder Finland condemned the DRPK's nuclear test, and said the act jeopardized regional stability and represented a severe threat to international peace and security.

It affirmed the 25-nation bloc's willingness to cooperate closely with the international community to respond to the issue, and strongly urged the DPRK to refrain from any further tests of nuclear devices, to publicly renounce nuclear weapons and return to the six-party talks immediately.

The EU also demanded the DPRK to fully comply with the Non-Proliferation Treaty, and ratify the Comprehensive Nuclear-Test-Ban Treaty.

While attending a World Health Organization meeting in Geneva, French Foreign Minister Philippe Douste-Blazy considered the DPRK's move as "a very grave act for international security."

"The Security Council had warned the DPRK on Friday, October 6... Now, it is up to the international community to respond to this new situation and to give a firm response to Pyongyang: we will engage in, without delay, the consultation with other members of the UN Security Council and the countries in the region," Douste-Blazy said.

Germany on the same day resolutely criticized Pyongyang's nuclear test and called for the United Nations to take action.

"Today's nuclear test is a threat to the region and beyond," and Pyongyang was "following the wrong path into self-isolation," German Foreign Minister Frank-Walter Steinmeier said in a statement.

He urged the DPRK not to go on with any further tests of nuclear weapons and to halt its missile program.

Other European countries such as Belgium, Poland, the Czech Republic, Hungary, Sweden and Turkey also expressed severe concern over Pyongyang's move, officially denouncing the act as irresponsible and a threat to international peace and stability.

In Asia and the Pacific, Singapore, Indonesia, Cambodia, the Philippines, Vietnam, Pakistan, Australia, New Zealand and Bangladesh deplored the DPRK's nuclear test and voiced condemnation over the dangerous act.

Since 2003, China, the United States, Japan, Russia, and South Korea have held intermittent talks with the DPRK in the hope of persuading Pyongyang to quit nuclear weapons in exchange for economic aid and security guarantees.

In July, a Security Council resolution imposed limited sanctions on the DPRK and demanded that the country return to the negotiating table, but the appeal was turned down by Pyongyang.