Seoul, Dec 24 (IANS): Pyongyang is preparing for another nuclear test in the coming months, South Korean authorities said on Saturday following the detection of activity in North Korean atomic installations.

Seoul's National Intelligence Service (NIS) has observed ongoing movement of humans and vehicles at the Punggye-ri base, where the Kim Jong-un regime carried out their last two atomic tests in January and September, Yonhap News Agency reported.

Pyongyang is preparing to conduct another nuclear test at any moment and is only waiting for an appropriate political situation regarding South Korea and the US, NIS head Lee Byoung-ho said before a parliamentary committee.

North Korea defector Thae Yong-ho, the former number two in Pyongyang's delegation in London, told the committee on Saturday that the Kim regime is preparing to conduct another nuclear test around the South Korean presidential elections, which will take place in 2017.

The fresh atomic test is intended to showcase the regime's power amid the political crisis in neighbouring South Korea due to the corruption scandal involving President Park Geun-hye. Efe news reported.

Thae defected to South Korea in August, becoming the highest ranking officer until now to cross over from the North, and has been described as a criminal by Pyongyang.

In 2016, North Korea conducted its fourth and fifth nuclear tests - after previous ones in 2006, 2009 and 2013 - besides launching some 20 missiles, including some launched from submarines, and medium-range ballistic missiles.