North Korea 'preparing for second nuclear test'

South Korean and Japan monitored reports today of North Korea’s possible preparations for a second nuclear test, a day after the US confirmed that communist country had, as it claimed, detonated its first nuclear device.

Washington pressed forward with a round of diplomacy in Asia to address divisions over how to impose sanctions on the North in response to the test blast, with secretary of state Condoleezza Rice due to arrive in Japan tomorrow before travelling to South Korea and China.

China, whose support for the measures is key to whether it will have any impact on neighbouring North Korea, has begun examining trucks at the North Korean border to comply with new United Nations sanctions endorsed over the weekend.

But China’s UN ambassador, Wang Guangya, said in New York that his country’s inspectors would not board ships to search for suspicious equipment or material.

Beijing’s mixed response on implementing the sanctions, approved Saturday by a unanimous UN Security Council including China, demonstrates the difficulties US diplomats will encounter as they tour the region.

In Tokyo, the Japanese government said today it had “information” concerning media reports that North Korea could be preparing for a second nuclear test.

“We have information but I cannot speak about its contents,” foreign minister Taro Aso said.

A South Korean government official in Seoul said his government was also aware of signs related to possible preparations for an additional North Korea nuclear test. The official said various intelligence reports were coming in about a possible test, but that it was unclear how reliable they were.

Seoul has already taken measures to be more vigilant for a possible second nuclear test by North Korea, and was bolstering exchanges of intelligence with the United States, the official said.

In Washington, US national intelligence director John Negroponte’s office said air samples gathered last week contained radioactive materials that confirmed that North Korea conducted an underground nuclear explosion.

In a short statement posted on its website, Negroponte’s office also confirmed that the size of the explosion was less than 1 kiloton, a comparatively small nuclear detonation. Each kiloton is equal to the force produced by 1,000 tons of TNT.

It was the first official confirmation from the United States that a nuclear detonation took place, as Pyongyang has claimed.