South Korea has stepped up its monitoring of North Korea's nuclear activities following reports that Pyongyang may be preparing to test an atomic bomb, a news report said Sunday.
The South has recently stationed six military personnel at a state-run seismology center to be on constant lookout for a possible nuclear test by the North, Yonhap news agency said, quoting an unnamed government source.
"The defense ministry is on a 24-hour vigil to deal with North Korea's potential nuclear test," the source told Yonhap, confirming the rare military dispatch to the Korea Institute of Geoscience and Mineral Resources.
The institute based in Daejeon, located 160km south of Seoul, monitors seismic tremors on the Korean Peninsula through detection facilities nationwide, including those along the border.
The ABC television network reported on Thursday that Pyongyang may be preparing an underground nuclear test. The governments in both Seoul and Washington remain cautious about the authenticity of the report.
The ABC said a US intelligence agency had recently observed "suspicious" activities.
US President George W. Bush, while refusing to verify the intelligence report, warned on Friday: "If North Korea were to conduct a test, it's just a constant reminder for people in the neighborhood, in particular, that North Korea poses a threat."