The Democratic People's Republic of Korea (DPRK)'s nuclear test on Monday aroused serious concern in South Korea, prompting President Lee Myung-bak to say it is a "serious threat and a "challenge".

President Lee also said that South Korea will call on the United Nations Security Council (UNSC) to take countermeasures on the issue.

The National Defense Committee of South Korea's National Assembly also adopted a resolution on Monday, which strongly condemned the DPRK and urged governments around the world to take prompt and stern countermeasures against the DPRK.

South Korean politicians, including those of the Grand National Party and the Democratic Party, raised voices against the DPRK, claiming that Monday's nuclear test threatened the peace and stability on the Korean Peninsula.

South Korea's weather agency said in the morning that it has detected an "artificial earthquake" around local time 09:54 a.m. (0054 GMT) Monday near Poongkye-ri in North Hamkyong Province in the DPRK.

The magnitude of the earthquake was estimated at 4.5 on the Richter scale, according to the weather agency. Poongkye-ri is known to be the area where the DPRK conducted its first nuclear test on Oct. 9, 2006.

Later, the DPRK's official Korea Central National Agency (KCNA) confirmed the report and called it its successful 2nd nuclear test.

South Korea's presidential office also said it immediately called for an emergency security meeting among related ministries and later an emergency National Security Council (NSC) meeting at local time 13:00 (0400 GMT) convened by President Lee Myung-bak.

"The latest nuclear test could have resulted in a force of up to 20 kilotons," which is around 20 times what the DPRK's 2006 explosion yielded, South Korean Defense Minister Lee Sang-hee was quoted as saying by Yonhap.

As a countermeasure, the South Korean government announced to disallow its civilians from visiting the DPRK, excluding the Kaesong Joint Complex, and banned non-priority facility items to go into the North, which is expected to harm inter-Korean trades.

On April 5, 2009, the DPRK carried out a rocket launch, arousing serious concern of various sides.

The UN Security Council on April 13 adopted a presidential statement on the April 5 launch by the DPRK, saying it is "in contravention of Security Council resolution 1718" and urging the early resumption of the six-party talks.

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

Source:Xinhua