The chief of the International Atomic Energy Agency(IAEA) said that there are indications of continued operation of the uranium enrichment facility at the Yongbyon nuclear site in North Korea.

IAEA Director General Rafael Grossi presented the assessment in his introductory statement at a session of the agency's Board of Governors on Monday in Vienna.

Grossi told the session that there are ongoing indications that the five-megawatt reactor is operating.

The IAEA chief said the agency also observed indications that the Centrifuge Enrichment Facility at Yongbyon continues to operate and is now externally complete, expanding the building’s available floor space by approximately one-third.

Grossi also said there are indications that Tunnel Number Three at the Punggye-ri nuclear test site has been reopened and that the site remains active and prepared to support a test.

He said that the agency has very recently observed renewed work on the road leading to Tunnel Number Four, characterizing the reopening of the nuclear test site as "deeply troubling."