A US delegation has visited North Korea's Yongbyon nuclear complex, the first time
outsiders have been allowed into the plant since UN inspectors were expelled a year ago.
The United States suspects North Korea may have resumed reprocessing spent nuclear fuel rods from Yongbyon into plutonium for use in nuclear weapons, and analysts said the trip to the facility may shed light on the North's nuclear capabilities.
"We did go to Yongbyon," delegation head Mr John Lewis told reporters in Beijing upon arrival from the North Korean capital, Pyongyang.
Mr Lewis and others on the unofficial delegation said they did not wish to comment on what they saw or discussed with officials until they had briefed the US government.
The five-day visit by a group that also included two US Senate aides, a nuclear specialist and a former State Department envoy for North Korea, came as the United States and its allies tried to reconvene talks with North Korea to end its suspected nuclear arms programme.
Mr Frank Jannuzi, a Senate Foreign Relations Committee aide, characterised the trip as "a good visit, a productive visit".
But it was not yet clear if, or how, it would benefit the process of talks on North Korea's nuclear weapons ambitions, analysts said.