South Korea's president says there are signs that North Korea is preparing a fifth nuclear test.

President Park Geun-hye said Monday that North Korea could carry out such a test to try to bolster its internal solidarity amid tough international sanctions imposed over the fourth atomic test and rocket launch conducted earlier this year.

Park didn't elaborate on what signs pointed to another nuclear test, but ordered the military to be ready to deal with any provocation by Pyongyang.

Speculation about a fifth nuclear test increased last month when the North's state media cited leader Kim Jong Un as ordering a test of a nuclear warhead.

Analysts say the atomic test could happen before the country holds a landmark ruling Communist Party congress in Pyongyang in early May.