The top U.S. nuclear envoy for North Korea said disablement of that country's atomic program is continuing on schedule, according to AP. Christopher Hill, who delivered an unprecedented letter from U.S. President George W. Bush to North Korean leader Kim Jong Ill during his visit this past week in Pyongyang, also urged the North to provide a «complete and correct» disclosure of its nuclear programs. «As important as the declaration is, it's also important to understand that actual work is on the ground in Yonbyong and is proceeding very much on schedule,» Hill said Friday during a transit stop in Japan following his three-day North Korea visit to inspect the North's nuclear disablement process at its main facility in Yonbyong. Under a six-nation agreement in February, North Korea was promised energy assistance and political concessions in return for disabling its nuclear programs. Efforts to produce a draft declaration of all its nuclear facilities by a year-end deadline appeared to have hit a snag, but Hill reiterated Friday he still has hope that North Korea will produce a substantive document. «I do believe they can have a draft produced before the end of the year,» he told reporters after meeting with his Japanese counterpart, Kenichiro Sasae, at Narita International Airport near Tokyo before flying back to Washington. The two envoys shared «strong hope» they would obtain North Korea's full declaration, and agreed to cooperate to achieve the goal, Sasae said. Hill said work to disable North Korea's Yongbyon nuclear plant is «moving quite on schedule» and workers are cleaning up contaminants before removing the fuel from the reactor, considered a key disabling step. «As I understand, all the equipment is in and the cleanup is almost ... completed or soon to be completed. So I think we can expect discharging of fuel to get under way very soon if it has not gotten under way now,» Hill said. Potential complications include North Korea's alleged uranium enrichment program and the true amount of separated plutonium that it declares. The U.S. accused North Korea in late 2002 of seeking to secretly enrich uranium in violation of an earlier disarmament deal, sparking the latest nuclear standoff. In his letter, Bush said North Korea's declaration must be «complete and accurate if we are to continue our progress,» according to an excerpt obtained by The Associated Press. Bush also sent similar letters to Russia, China, South Korea and Japan, the other participants the six-nation North Korean disarmament talks. Pyongyang conducted its first nuclear test explosion in October 2006, prompting international condemnation and sanctions. Relations between the U.S. and North Korea have improved since Pyongyang began disabling its reactor, which was shut down in July, and two other facilities.