Seoul: Recent satellite images show North Korea is digging a new underground tunnel in what appears to be preparation for a third nuclear test, according to South Korean intelligence officials.

READ MORE: N Korea:Satellite Image of rocket site 

The excavation at North Korea's northeast Punggye-ri site, where nuclear tests were conducted in 2006 and 2009, is in its final stages, according to a report by intelligence officials that was shared on Monday. 
   
Its release comes as North Korea prepares to launch a long-range rocket that Washington and others say is a cover for testing missile technology that could be used to fire on the United States.
   
Observers fear a repeat of 2009, when international criticism of the North's last long-range rocket launch prompted Pyongyang to walk away from nuclear disarmament negotiations and, weeks later, conduct its second nuclear test. A year later, 50 South Korean were killed in attacks blamed on the North.
   
"North Korea is covertly preparing for a third nuclear test, which would be another grave provocation," said the report, which cited US commercial satellite photos taken April 1. "North Korea is digging up a new underground tunnel at the Punggye-ri nuclear test site, in addition to its existing two underground tunnels, and it has been confirmed that the excavation works are in the final stages."
   
Dirt believed to have been brought from other areas is piled at the tunnel entrance, the report said, something experts say is needed to fill up underground tunnels before a nuclear test. The dirt indicates a "high possibility" North Korea will stage a nuclear test, the report said, as plugging tunnels was the final step taken during its two previous nuclear tests.
   
North Korea announced plans last month to launch an observation satellite using a three-stage rocket during mid-April celebrations of the 100th anniversary of the birth of North Korean founder Kim Il Sung.
   
The US, Japan, Britain and other nations have urged North Korea to cancel the launch, warning that firing the long-range rocket would violate UN resolutions and North Korea's promise to refrain from engaging in nuclear and missile activity.

China remains 'worried'

China's Foreign Minister said his country was "worried" by North Korea's impending rocket launch, as the regime in Pyongyang again insisted it was to send a peaceful satellite and not a missile.       

Yang Jiechi told his South Korean and Japanese counterparts on Sunday that peace on the Korean peninsula was in the interests of all, according to a Foreign Ministry statement.
      
"Yang Jiechi said China is concerned and worried about the developments on the issue," said the statement, released late on Sunday after the three ministers met in the eastern Chinese city of Ningbo.
      
"China calls upon relevant parties to focus on the overall situation and look in the long-term, and to remain calm and exercise restraint and to use diplomacy and peaceful means to adequately resolve relevant problems."
     
Concerns are growing over North Korea's rocket launch, slated between April 12 and April 16, despite assurances from the nuclear-armed nation that it was to send a peaceful scientific satellite and not a ballistic missile.
      
Japan has deployed missile batteries to protect Tokyo and dispatched three Aegis destroyers carrying interceptor missiles, reportedly to the East China Sea.
      
Japanese Prime Minister Yoshihiko Noda has given the green light to shoot down the rocket if it threatens Japan's territory.
   
The secretive North Korean regime organised an unprecedented visit for foreign reporters to the Tongchang-ri space centre to disprove missile test claims by the US and its allies, where its head called the accusations "nonsense."
   
Yang also called for the resumption of six-party talks involving North and South Korea, the US, China, Russia and Japan, stalled since the last meeting in December 2008.

(Agencies)