South Korea has warned that North Korea is gearing up to conduct another nuclear test and said they are closely monitoring the situation. If Pyongyang carries out one more nuclear detonation, which would be the reclusive nation's fifth, it is certain to further escalate tensions in the Korean peninsula.

Seoul's unification ministry said during a routine press conference that Pyongyang is fully equipped to conduct another test and is only awaiting an order from the country's leader Kim Jong-un.

"North Korea seems to be fully prepared to carry out a nuclear test at any time (when the order is given by its leader Kim). South Korea is closely monitoring every move at the North's test site in close cooperation with the United States," said the ministry, according to Yonhap news agency, without divulging more details about the possibility.

The latest development has come when increased activity was reported at the North's usual nuclear test site of Punggye-ri. Heavy traffic was reported in the region which could also indicate routine maintenance work.

The Korean peninsula already remains volatile owing to a flurry of activity in the last several months. Pyongyang carried out its fourth nuclear test in January 2016 and its previous three explosions were conducted in 2006, 2009 and 2013.

Pyongyang, which was reportedly enraged by the US and South Korean decision to deploy sophisticated Terminal High Altitude Area Defence (Thaad) missiles in the region, threatened to take "physical action" against its adversaries.

North Korea nuclear test
North Korean leader Kim Jong-un smiles as he attends a flight training session by female fighter pilots Jo Kum Hyang and Rim Sol in this undated photo KCNA via Reuters