The chief U.S envoy in talks to get North Korea to give up its nuclear weapons says his discussions with officials in Pyongyang covered a lot of ground.  He says he has great concern about moves to restart North Korea's main facility for producing material useable in nuclear weapons. VOA's Kurt Achin reports from Seoul.

U.S. Assistant Secretary of State Christopher Hill returned to South Korea Friday from three days and two nights in North Korea, where he says he discussed the issue of nuclear verification with leaders there.

North Korea submitted a declaration of its nuclear activities earlier this year as part of a broader six-nation deal aimed at ending its nuclear weapons capabilities altogether.  Hill says he spent much of his visit discussing the North's refusal to agree to a set of steps for confirming the accuracy of that document.

"The discussions in Pyongyang were quite substantive, we went into great detail on things," he said.  "They were quite lengthy... needless to say, there's been a lot of problems in the six-party process, so indeed we did quite a substantial review of activities in the last couple months."

In August, President Bush decided not to remove North Korea from a State Department list of nations suspected of sponsoring terrorism.  Washington promised that step as a reward for submitting the nuclear declaration, but says keeping that promise will not be possible unless the declaration is verified using internationally accepted methods, possibly including random inspections of nuclear sites.

North Korea responded by reversing earlier steps it took to disable its primary nuclear facility at Yongbyon.  Last week it ejected international inspectors and their surveillance equipment from the site. Pyongyang warned it would resume reprocessing of spent nuclear fuel into material useable for weapons by the end of this week.

Hill says he cannot confirm whether that is actually happening.  "I don't have any update of what is going on in Yongbyon, obviously the issue in Yongbyon is an issue that has been of great concern to us and obviously that is one of the points that I conveyed," he said.

Hill was unwilling to provide details Friday about what sort of compromise verification measures he may have proposed to North Korea.  He says he needs to brief other leaders in the six-nation process before fully disclosing the content of his discussions.  After briefing his Japanese counterpart Friday night, Hill is scheduled to travel to Beijing on Saturday, then return to Washington to confer with Secretary of State Condoleezza Rice.