The Democratic People's Republic of Korea, DPRK (commonly known as North Korea), has the ability to double its nuclear explosion potential in its next nuclear test, Seoul's intelligence authorities claimed on Wednesday, while also warning of important advances in Kim Jong-un's nuclear program.

"Should the North conduct a fourth round of nuclear tests, the explosion would have a force of at least 10-15 kilotons," an official from South Korea's National Intelligence Service, NIS, told the local Yonhap news agency.

The figures calculated by Seoul represent twice the 6.7-kiloton yield of North Korea's most recent nuclear test, carried out in February 2013, which caused seismic tremors of 4.5 degrees on the open-ended Richter scale.

Two earlier nuclear tests conducted by Pyongyang in 2006 and 2009 were estimated to have a yield of 1 and 3.5 kilotons, respectively.

The South Korean intelligence official said that the NIS has not detected any unusual movements at the Punggye-ri base, in northeastern North Korea, where Pyongyang has carried out all its earlier nuclear tests.

However, satellite images taken over the last few months revealed high activity in North Korean nuclear installations.

Experts are of the opinion that the communist regime could carry out its fourth nuclear test at any time and without prior warning.

The NIS official also said that North Korea had recently tested powerful explosives in its capital, Pyongyang, as part of its project to miniaturize weapons for its atomic program.

Though the North Korean regime has demonstrated its ability to carry out nuclear explosions, it remains to be seen whether it has made sufficient technological advances to reduce the size of atomic heads and install them on long-range missiles.