'Signs' N. Korea preparing nuclear test

North Korea is showing "signs" of preparing a fourth nuclear test, South Korean Unification Minister Ryoo Kihl-Jae said Monday, with reports of stepped up activity at its main atomic test site.

"There are such signs," Ryoo told a parliamentary committee hearing when lawmakers asked him to confirm the reports.

Ryoo declined to elaborate, saying it would be inappropriate "to comment further here on matters related to intelligence".

The daily JoongAng Ilbo on Monday had cited intelligence reports showing a sharp increase in activity at the North's Punggye-ri nuclear test site since last week

"We are closely monitoring the ongoing situation, which is very similar to the situation seen ahead of the third nuclear test," the newspaper quoted a senior government official as saying.

"We are trying to figure out whether it is a genuine preparation for a nuclear test or just a ploy to heap more pressure on us and the US," the unnamed official added.