SEOUL, Sept. 12 (Xinhua) — South Korea's military said on Monday that the Democratic People's Republic of Korea (DPRK) is ready to conduct another nuclear test following its fifth nuclear detonation.

Defense Ministry spokesman Moon Sang-kyun told a press briefing that intelligence authorities of South Korea and the United States are assessing the DPRK is "always ready" to carry out additional nuclear test in its main Punggye-ri nuclear test site.

His comments followed the DPRK's announcement on Friday that it successfully staged an explosion test of a nuclear warhead that can be mounted on ballistic missiles "at will."

The warning of additional test is based on three tunnels excavated at Punggye-ri in northeastern DPRK, near which all of its underground nuclear tests were conducted.

"If the DPRK conducts additional nuclear test, it would be possible to happen both from a branch of the second tunnel or the third tunnel where all preparations are already done," said Moon.

All of Pyongyang's nuclear device tests happened in Punggye-ri. The first test was conducted in the first tunnel, while the second, the third and the fourth detonations came from the second tunnel.

The site of the fifth nuclear test is some 500 meters away from where the fourth test was conducted, according to Yonhap news agency report citing unnamed government sources.

Pyongyang reportedly completed all preparations for a nuclear test at the third tunnel, where any atomic device test hasn't occurred yet.