North Korea conducts nuke test

South Korean government officials said North Korea performed its first-ever nuclear weapons test Monday, the South's Yonhap news agency reported.

South Korean officials could not immediately confirm the report.

South Korean President Roh Moo-hyun convened an urgent meeting of security advisers over the issue, Yonhap reported.

The North said last week it would conduct a nuclear test as part of its deterrent against a possible U.S. invasion.