South Korea's president says there are signs that the Democratic People's Republic of Korea is preparing a fifth nuclear test. President Park Geun-hye said the test is an attempt to bolster internal solidarity as the DPRK faces tough international sanctions imposed over its earlier nuclear test and rocket launch.

Park didn't elaborate on what signs pointed to another nuclear test. The South Korean defence ministry says there's evidence based on recent activity around the DPRK nuclear test site, which the South Korean military is closely monitoring. Analysts say the atomic test could happen before the DPRK holds a landmark ruling Communist Party congress in Pyongyang in early May.