North Korea preparing nuclear test, South Korea says
North Korea may be preparing for a fourth nuclear test, South Korean officials say.
South Korean Unification Minister Ryoo Kihl-jae told lawmakers there are "signs" of increased activity in the North's main nuclear test site.
A newspaper also quoted a South Korean official confirming activity similar to the North's third test on 12 February.
This comes amid North Korea's stepped up rhetoric in recent weeks against the US and South Korea.
Mr Ryoo did not elaborate on the specific intelligence.
But when asked about a news report that North Korea had stepped up activity at its underground atomic test site, he said "there are such signs".
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