The International Atomic Energy Agency(IAEA) reported that preparations for a seventh nuclear test appear to be under way with the detection of ongoing activity at North Korea's Punggye-ri nuclear test site.

Speaking at a regular board meeting in Vienna on Monday, IAEA Director General Rafael Grossi said there are continued signs of activity near Tunnel Number Three and other areas where support work takes place.

He stressed that a resumption of operations at the site is a violation of UN Security Council resolutions and will trigger serious concerns.

Regarding the North's Yongbyon nuclear complex, Grossi said that facilities there have been continuously operating since March of this year and signs of increased construction have been observed.

On-site inspection of North Korea's nuclear facilities has long been suspended after the regime rejected IAEA safeguards in 2009 and announced its withdrawal from the Non- Proliferation Treaty in 2003.