South Korean President Lee Myung-bak convened an emergency meeting of the National Security Council, an official said, as an artificial tremor in North Korea suggests that the communist nation went ahead with a threatened nuclear test.

   Lee will convene the meeting at 1 p.m., the official said.

   A magnitude 5.1 tremor occurred at 11:58 a.m. and was centered in Kilju County in North Korea's northeast, where the country's Punggye-ri nuclear test site is located, officials said. The government is analyzing earthquake waves, they said. (Yonhap)