The Democratic People's Republic of Korea (DPRK) said it successfully conducted a nuclear test on Monday, arousing immediate concerns and various responses from the world community.

UN Secretary General Ban Ki-moon said in Copenhagen that he was "deeply disturbed" by the nuclear test, telling reporters that he was closely following the events.

The UN Security Council would hold an emergency meeting on Monday to discuss the nuclear test.

South Korea's Defense Ministry said Monday it launched a "crisis management team" of general-level officers.

"The team will come up with measures to respond to the nuclear test," said Lee Bung-woo, a spokesman at the Ministry of National Defense, adding the military is yet to put its troops on heightened alert.

Japanese Prime Minister Taro Aso said Monday that the DPRK nuclear test is a "grave challenge" to the Nuclear Non-Proliferation Treaty regime and a "clear violation" of a UN Security Council resolution banning the country from nuclear activity.

The Japanese government has set up a special task force at the emergency management center of Prime Minister Aso's office.

U.S. President Barack Obama condemned the test as a "threat to international peace and security."

The behavior increases tensions and undermines stability in Northeast Asia, said Obama in an immediate statement, adding that such provocations will only serve to deepen the DPRK's isolation.

The Russian Foreign Ministry voiced concern about the test, saying that the nuclear test threatens regional stability, violates the will of the UN Security Council and is a blow to non-proliferation efforts.

The European Union (EU) also expressed concerns about the development.

EU foreign policy chief Javier Solana branded Monday the nuclear test as "irresponsible acts," and called for a tough response from the international community.

These irresponsible acts by the DPRK warrant a firm response by the international community, Solana said in a statement, adding the EU will be in contact with its partners to discuss appropriate measures.

The reported nuclear test is "very, very worrying," EU external relations commissioner Benita Ferrero-Waldner said Monday.

Major European powers all condemned the nuclear test in strongest terms.

The German government called the test as an "irresponsible provocation" that threatens international stability.

British Prime Minister Gordon Brown denounced the nuclear test on Monday as a "danger to the world" that will undermine peace prospects on the Korean peninsula.

"I condemn North Korea (DPRK)'s nuclear test in the strongest terms as erroneous, misguided and a danger to the world," Brown said in a statement.

"This act will undermine prospects for peace on the Korean peninsula and will do nothing for North Korea (DPRK)'s security," he said.

The French government Monday called on Pyongyang to "refrain from any new provocation."

In a statement issued by the Foreign Ministry, the French government called on the DPRK "to resume discussions within the Group of Six with the aim of the complete, irreversible and verifiable dismantling of its nuclear program."

The DPRK said on Monday it successfully conducted "one more" underground nuclear test earlier in the day.

In a statement released by the official news agency KCNA, the DPRK government said the test was "part of the measures to bolster up its nuclear deterrent for self-defence in every way as requested by its scientists and technicians."

"The current nuclear test was safely conducted on a new higher level in terms of its explosive power and technology of its control and the results of the test helped satisfactorily settle the scientific and technological problems arising in further increasing the power of nuclear weapons and steadily developing nuclear technology," the statement said.

But the brief statement did not give any details about the test, including its location.

The Seoul-based Korea Meteorological Administration said it detected an "artificial earthquake" of 4.5 magnitude around local time 09:54 a.m. (0054 GMT) Monday in North Hamkyong Province, 10 to 15 km away from the site where the DPRK staged its first nuclear test in 2006.

The test came after the UN Security Council adopted a presidential statement in late April, condemning the April 5 rocket launch by the DPRK and demanding the country "not conduct any further launch."

Pyongyang subsequently announced it was quitting the six-party talks on nuclear disarmament and would restart nuclear facilities in protest of the UN statement.

(Xinhua News Agency May 25, 2009)