By Deutsche Presse Agentur
Earlier UN's Comprehensive Nuclear-Test-Ban Treaty Organization said North Korea was suspected to have carried out its third atomic test Tuesday after a seismic shock was registered.
"The event shows clear explosion-like characteristics and its location is roughly congruent with the 2006 and 2009 DPRK nuclear tests," he said in Vienna, using the official acronym of the Democratic People's Republic of Korea.
The United States Geological Survey reported a magnitude-4.9 quake in north-east North Korea. South Korean sources put the figures lightly higher.
South Korea's Defence Ministry estimated the yield of the weapon to be 6-7 kilotons, Yonhap News Agency reported.
The UN Security Council was to meet Tuesday following a request from Seoul, a South Korean diplomat told Yonhap. President Lee Myung Bak ordered a meeting of South Korea's security council in response to the apparent test.
Japan was also expecting a stern response from the Security Council, chief cabinet secretary Yoshihide Suga said.
The United States told Japan on Monday that Pyongyang would conduct a nuclear test in the near term, he added.