The Institute for Science and International Security released a report on Wednesday finding that the area of the Yongbyon reactor complex responsible for enriching uranium is now twice as large as it was in the past.
According to the New York Times, the report by the Washington-based, nonproliferation-monitoring group triggers new worries that North Korea is expanding its capacity to produce weapons-grade fuel.
The analysis was based on a comparison of satellite images of the complex taken in March -- before construction began on the expansion -- and on a June image that shows the framework of the addition, which is roughly the same size as the initial centrifuge facility.
Additional proliferation experts agreed with the ISIS analysis that the uranium-enrichment portion of the site appears to have doubled in size, the Times reported.
The expanded facility could produce anywhere from 16 to 68 kilograms of weapons-grade uranium, enough to manufacture two nuclear weapons per year, the ISIS report states.
North Korea asserts that the centrifuge facility produces low-enriched uranium for an onsite experimental light water reactor at the complex. However, it is unclear how extensive the North's enrichment capacity has become and whether the isolated nation has produced weapon-grade uranium -- and, if so, how much, according to the analytical organization.
North Korea has faced sanctions from the United Nations aimed at preventing the North from acquiring specialty metals and centrifuge components from overseas. Pyongyang might have been able to develop ways of producing these materials domestically, according to the newspaper.
The news comes less than two weeks after North Korea's leader Kim Jong Un told the Chinese vice president that he was open to restarting denuclearization discussions, and just a day after the North proposed another round of talks with South Korea with the intent of reopening a shuttered factory complex operated jointly by the two nations.