North Korea has taken dramatic steps toward fulfilling its threat to resume production of nuclear weapons material.  VOA's Kurt Achin reports from Seoul.

North Korea's spent nuclear fuel rods kept in cooling pond are seen at nuclear facilities in Yongbyon,  in this 1996 file photo, released from Yonhap

The International Atomic Agency, or IAEA, confirms North Korea has ended international supervision of activities at its main nuclear reprocessing facility in Yongbyon.  Melissa Fleming, a spokeswoman for the U.N. agency, confirms it has complied with North Korea's demand to remove seals and cameras.

"There are no more seals and surveillance equipment in place at the reprocessing facility," she said.

Fleming says the North has disclosed plans for the facility in the near future.

"The DPRK has also informed the IAEA inspectors that they plan to introduce nuclear material to the reprocessing plant in one week´s time," she said.  "They further stated that from here on the IAEA inspectors will have no further access to the reprocessing plant."

South Korean officials say they are very concerned about North Korea's actions, which pose a serious challenge to an international deal aimed at ending its nuclear weapons capabilities.

Pyongyang promised South Korea, the United States, Japan, China and Russia last year it would fully disable the Yongbyon facility, and declare its nuclear programs as a step toward eliminating them altogether.  After submitting the declaration months past the agreed deadline, North Korea has refused to agree on a set of steps for outside teams to verify that the declaration is accurate.

The United States says it will not remove North Korea from a State Department list of nations accused of sponsoring terrorism until there is a verification agreement.  North Korea says the verification issue is separate from Washington's promise to remove it from the terror list.  In recent weeks, it has threatened to restart the Yongbyon reactor, and says it is no longer interested in being removed from the U.S. list.

South Korea has hinted it may delay energy and other assistance it committed to provide North Korea under the six-nation deal.  That could further constrict North Korea's impoverished economy, which has endured strict international sanctions since Pyongyang tested its first nuclear weapon in 2006.