The United States has urged North Korea not to proceed with a suspected new nuclear test. As concern mounts over a planned rocket launch, Pyongyang is also accused of planning an underground detonation.
Washington said on Monday it would consider an underground test by North Korea as "highly provocative," amid reports that Pyongyang was preparing an underground nuclear detonation.
The warning was made in tandem with an appeal for North Korea not to press ahead with a rocket launch that the West fears may be a cover for a ballistic missile test.
"In each case this would be an indication of North Korea's decision at the leadership level not to take the steps that are necessary to allow North Korea to end its isolation, to rejoin the community of nations," White House spokesman Jay Carney told a Washington news briefing.
North Korea announced its plans last month for the rocket launch, which the US and Japan have urged the country to cancel, but news of the suspected nuclear test only emerged on Sunday.
In relation to the rocket test, US State Department spokeswoman Victoria Nuland said that a third nuclear test would be "equally bad, if not worse."
Clandestine nuclear test
South Korea's Yonhap news agency quoted an unidentified South Korean intelligence source claiming that North Korea was "clandestinely preparing a nuclear test." It said the detonation was planned at the same location where North Korea's first two tests - in 2006 and 2009 - were held.
The excavation at the northeastern Punggye-ri site, was reported to be in its final stages.
"North Korea is covertly preparing for a third nuclear test, which would be another grave provocation," the intelligence report was cited as saying on the basis of US commercial satellite photos taken on April 1.
"North Korea is digging up a new underground tunnel at the Punggye-ri nuclear site in addition to its existing two underground tunnels, and it has been confirmed that the excavation works are in the final stages."
Dirt was reported to be being piled at the tunnel entrance, the report said. This is something experts say is needed to fill up tunnels before a detonation, indicating a "high possibility" that a test will be staged.
North Korea said it would launch its rocket - which it says is a peaceful satellite launch - to coincide with celebrations of the April 15th hundredth anniversary of the birth of North Korean founder Kim Il Sung.
rc/slk (AFP, AP, Reuters)