North Korea is preparing to conduct a third nuclear test at the same site where it had carried out its two previous tests say reports from South Korean media. The news further complicates an already tense situation in the Korean peninsula, following the North's decision to go ahead with its controversial rocket launch plan.

South Korean news agency Yonhap reported that there was evidence of North Korea digging a tunnel at the same site in Punggye-ri, in the country's north-east region where nuclear tests were conducted in 2006 and 2009.

Fresh evidence came to light from satellite images that showed a huge pile of loose earth in front of a tunnel at the nuclear test site indicating on-going construction of a new underground tunnel. Experts believe that North Korea will use the newly built tunnel to conduct its third underground nuclear test.

South Korean intelligence officials have accused Pyongyang of using international criticism against its April rocket launch plan as an excuse to go ahead with the nuclear test.

The reports, if true, would result in an international agitation against the reclusive country. The move will further deteriorate the already strained relations between the country and its neighbors.

North Korea had announced that it would launch a weather satellite using its Unha-3 rocket into the polar orbit in the second week of April to commemorate the birth centenary celebrations of its founder president Kim Sung-II. However, South Korea and the West have condemned the move saying that North Korea is actually testing its long-range ballistic missile under the pretext of a satellite launch.

Meanwhile, a report in the Washington Times, quoting South Korean media, says that there is evidence of North building an Inter Continental Ballistic Missile (ICBM). According to the report, US intelligence sources have also reported that North Korea is developing a road-mobile ICBM that can reach US targets.