WASHINGTON : The coming two weeks will be "a very important period" for international efforts to secure North Korean nuclear disarmament, said Christopher Hill, America's lead negotiator in six-party nuclear talks.

He was speaking in Washington after his trip to East Asia, which included a surprise visit to Pyongyang.

United Nations inspectors are due to arrive in North Korea to discuss the shut down of North Korea's nuclear facilities at Yongbyon.

Mr Hill, US Assistant Secretary of State for East Asian and Pacific Affairs, went to the State Department to assess the way forward, ahead of the visit to North Korea by officials of the International Atomic Energy Agency.

He said: "Assuming all goes well in the next, I think it's a four-day visit, we would then look forward to the shut down beginning at some point after that. We would then hope to have a six-party meeting of some kind - head of delegations, informal, formal - probably in the second week in July."

Ambassador Hill said that if things go well, the facilities at Yongbyon could be shut down and disabled by the end of this year.

Mr Hill said: "Disabling has got to be defined...Obviously the more extensive the disabling, the better from our point of view."

Once the reactor is shut down, Mr Hill said negotiators expect it to be made so that it cannot be brought back online without an enormous repair bill.

Despite the fairly positive tone, the Bush administration's point man on North Korea anticipated hard times ahead.

Mr Hill described the shut down of Yongbyon as just the first step among many, albeit a very important one.

He also expected each step to be more difficult than the one before. - CNA/ch