North Korea's official Korean Central News Agency (KCNA) reported Monday the country has performed a successful nuclear test.

South Korean government officials also said North Korea performed its first nuclear test, the South's Yonhap news agency reported

According to KCNA, there was no radioactive leakage from the site.

South Korean officials could not immediately confirm the Yonhap 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.

The report of the test came as Japan's new Prime Minister Shinzo Abe arrived in Seoul for meetings with President Roh Moo-hyun to address the nuclear issue as well as address strains in relations between the two countries over territorial and historical disputes.

North Korea accused rival South Korea on Monday of committing a serious provocation by firing warning shots during a weekend incident in which the South says soldiers from the communist North crossed over their border.

The border shooting came Saturday. South Korean soldiers rattled off about 40 warning shots after a group of five North Korean troops crossed into the southern side of the no-man's-land separating the divided Korean peninsula, South Korea said.