A secret facility used by North Korea in the early stages of building its program to enrich uranium for nuclear weapons has been found by a U.S. policy institute, Reuters reported Thursday. The news comes weeks after Pyongyang warned the United States of more nuclear tests and missile launches if Washington continues in its attempts to weaken the North Korean government through its policy of pressure and punishment.

The Institute for Science and International Security said in its report that if the facility is confirmed, it would be critical to the success of any future nuclear deal. According to the report, authorities have always been in doubts about whether North Korea has disclosed all of its nuclear facilities. The secret facility has been reportedly found about 27 miles from the nuclear complex at Yongbyon. The institute’s report also claimed that the site may be at its early stage of the development of centrifuges that refine uranium hexafluoride gas into low-enriched and highly enriched uranium.

"It is necessary to identify where North Korea enriches uranium and part of that is understanding where it has done it in the past," David Albright, the institute's president, said.

North Korea's early centrifuge research and development facility was previously believed to have been inside an aircraft part factory inside a mountain next to Panghyon Air Base, the report seen by Reuters stated, adding that it was located using commercial satellite imagery. However, it was unclear if the aircraft part factory was still operational.

Tensions have been escalating in the Korean Peninsula, after Pyongyang carried out its fourth underground nuclear test in January followed by a series of missile launches.

In November 2010, North Korea revealed the existence of a production-scale gas centrifuge plant at Yongbyon, adding that it had no other such facilities. 

The new report, which cited an unidentified official, said that the site could have held between 200 and 300 centrifuges.

North Korea's fourth nuclear test and a series of missile launches have been condemned by the international community while the reclusive country was slapped with harsh sanctions by the United Nations Security Council.

Last month, Pyongyang criticized the U.S. for its joint military drills with South Korean, holding Washington responsible for nuclear war threat on the Korean Peninsula. The North also reportedly said that the U.S. did not have any right to talk about its denuclearization — something that Washington has been seeking from the isolated country.