The International Atomic Energy Agency(IAEA) says the uranium enrichment facility that North Korean leader Kim Jong-un visited in September appears to be an undeclared annex of the Kangson Complex near Pyongyang. 

IAEA Director-General Rafael Grossi revealed the assessment in his opening remarks for the agency’s board of governors meeting in Vienna on Wednesday, noting that the IAEA is continuously monitoring the North’s nuclear program.

Grossi said “the depicted centrifuge cascades and infrastructure are consistent with the layout of a centrifuge enrichment facility and with the structure of the main building at the Kangson Complex and its newly constructed annex." 

He added that images showing the installation of centrifuges in the annex building coincide with Kim's orders to boost the production of nuclear weapons by significantly increasing the number of centrifuges. 

Grossi was referring to images that the North's state-run Korean Central News Agency previously released on September 13 of Kim visiting the facility without elaborating its location. 

The IAEA chief stressed that the disclosure of the undeclared facility in the Kangson Complex and Kim’s orders are a matter of "serious concern."

The Kangson Complex on the outskirts of Pyongyang has long been identified and monitored by U.S. intelligence authorities as a secret uranium enrichment in addition to the North's Yongbyon nuclear facility.