North Korea in nuclear test claim

(North Korea says it has carried out its first ever test of a nuclear weapon, the state news agency has reported)

It said the underground test, done in defiance of international warnings, was a success and had not resulted in any leak of radiation.

A South Korean official said an explosion had been detected in the north-east of North Korea, measuring 3.5 on the Richter scale.

North Korea said last week that it planned to test a nuclear weapon.

South Korean President Roh Moo-hyun has called an emergency meeting of his government's National Security Council.

A South Korean official said that there had been a grave change in the security situation on the peninsula.

Officials in South Korea have been quoted as saying that an explosion was detected in north Hamgyong province in North Korea.

South Korea's Yonhap news agency is reporting that the test took place in Gilju in Hamgyong province.

Prior to the test, there had been speculation that any such trial would take place either in Gilju or Hagap in the centre of the country.

The entire region has been on high alert since North Korea said last week it would conduct a nuclear test.

Japan's Prime Minister Shinzo Abe has just arrived in Seoul for a meeting with Mr Roh, following talks on the crisis with his Chinese counterparts in Beijing.

At the Beijing summit, Japanese and Chinese leaders had earlier said that such a test would be considered "unacceptable".

(A US military response to North Korea's move remains unlikely)

The North’s official Korean Central News Agency said the underground test was performed successfully and there was no radioactive leakage from the site.

• "If the North cannot or will not be restrained, then the world might one day have to live with the North Korean bomb"

South Korean intelligence officials said a seismic wave of magnitude-3.58 had been detected in North Hamkyung province, according to Yonhap. It said the test was conducted at 10:36 a.m. (9:36 p.m. EDT Sunday) in Hwaderi near Kilju city on the northeast coast, citing defense officials.

North Korean scientists “successfully conducted an underground nuclear test under secure conditions,” the KCNA report said, adding this was “a stirring time when all the people of the country are making a great leap forward in the building of a great prosperous powerful socialist nation.”

The director of South Korea’s monitoring center that is watching for a test with sound and seismic detectors declined to immediately comment on the reported test.

“We don’t know whether it is a nuclear test or not,” an official at the earthquake center at the Korea Institute of Geoscience and Mineral Resources said on condition of anonymity, citing the sensitive nature of the issue.

The U.S.