SEOUL (AFP) - North Korea has covered the entrance to a tunnel at its nuclear test site in an apparent effort to avoid satellite monitoring ahead of a widely expected detonation, a report said on Friday.
The Punggye-ri site, which has three tunnel entrances and multiple support buildings, has been closely monitored by US, South Korean and Japanese intelligence since North Korea ramped up its test threats just over a week ago.
"Analysis showed a camouflage net looking like a roof was placed on the tunnel entrance," Yonhap News Agency cited a senior South Korean government source as saying.
"The move seems to be aimed at keeping nuclear test preparations - now near their completion - from being exposed outside," the source said.
North Korea has threatened to carry out its third nuclear test in response to UN sanctions imposed on Pyongyang for a long-range rocket launch it carried out in December.
The North said the launch was a scientific mission aimed at placing a satellite in orbit, but most of the world saw it as a disguised ballistic missile test.
Yonhap quoted an intelligence source as saying the cover at the test site may be aimed at confusing outside watchers.
"It seems like a disturbance tactic, similar to one that was used when the North prepared the rocket launch," the source said.
The South's intelligence agencies had been embarrassed by the timing of the December launch, partly due to the North's use of camouflage at the launch site.
At one point, diplomatic and military sources suggested the launch was facing a lengthy delay, while some said the rocket had been completely removed from the pad.
The rocket blasted off a day later.