SEOUL, South Korea - US envoy Christopher Hill said Friday that North Korea is prepared to promptly close down its Yongbyon nuclear reactor in line with an agreement reached earlier this year.

In this image from television, Assistant US Secretary of State Christopher Hill , left, is greeted by an unidentified North Korean official, center, as he arrives at an airport in the North Korean capital of Pyongyang on Thursday June 21, 2007. [AP]

Hill, speaking at a press conference in Seoul following his return from the North, also said both the US and North Korea reaffirmed their commitment to the February accord aimed at North Korea's denuclearization as well as an early meeting of chief representatives to the six-way negotiating framework.

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"The talks were very detailed, very substantive and I believe they were also very useful and positive," Hill said at the joint press conference with his South Korean counterpart, Chun Yung-woo.

"The DPRK indicated that they are prepared promptly to shut down the Yongbyon facility as called for in the February agreement," Hill said.

Hill said the North is ready to disable the reactor, also in line with the agreement, "although we must work out the details."

While saying that North Korea's denuclearization can be achieved, Hill also said it will take time and effort.

"I sense that we are going to be able to achieve our full objectives, that is complete denuclearization, but, also burdened by the realization of the fact that we are going to have to spend a great deal of time, a great deal of effort, a lot of work in achieving these," Hill said.

In February, North Korea promised China, Japan, Russia, South Korea and the US, the other members of the six-way talks, to shut down its main nuclear facility at Yongbyon by mid-April.

That was delayed, however, due to a dispute over $25 million in allegedly illicit North Korean funds frozen in a bank in Macau.

Hill said he was invited to visit by North Korea and made no effort to meet North Korean leader Kim Jong Il.