A top U.S. official said Wednesday that work on disabling North Korea's main nuclear complex will probably begin this week, a step that would move the country one step closer to disarmament.

Assistant Secretary of State Christopher Hill said talks went well with his North Korean counterpart on the technical details of disabling a reactor that produces plutonium for bombs, as well as other facilities at Yongbyon nuclear complex.

"I think everything went smoothly. We weren't negotiating. We were more comparing notes," Hill told reporters. "We're at a phase now where we're talking a lot about nuts and bolts."

North Korean negotiator Kim Kye Gwan said no problems cropped up during talks with Hill, Japan's Kyodo News agency reported. "At this stage, there are no major differences in opinion," Kim said.

Under a February agreement, North Korea pledged to abandon its nuclear ambitions in exchange for the equivalent of 1 million tons of oil and political concessions.

The communist regime said it would disable the reactor, the reprocessing plant and the fuel fabrication plant in the Yongbyon complex, and declare all of its atomic programs, by the end of the year.

Hill said the talks focused on the scope of disabling the complex and communications logistics in preparation for a visit by a U.S.-led team of experts to North Korea on Thursday.

"There are three facilities in Yongbyon and there are some procedures that have been agreed on to take apart the equipment there," said Hill. "That will, we think, begin actually this week."

The U.S. team will carry out about 10 measures to disable the Yongbyon facilities, South Korean Foreign Minister Song Min-soon told reporters in Seoul.

He said the six countries involved in the nuclear negotiations — the two Koreas, the United States, Japan, Russia and host China — would meet later this year to discuss the next steps.

Hill said much needs to be done over the next couple of months and the six countries will have "even more work to do" next year. "That is the crucial and final phase which involves dismantlement and abandoning of all the weaponized plutonium," he said.

He said North Korea also reiterated "their assurances that ... they will not engage in any transfer of nuclear technology and material" to other countries.

North Korea provides missile technology to Syria but has strongly denied accusations that it spreads its nuclear expertise beyond its borders. Syria also has denied receiving any North Korean nuclear help or embarking on any nuclear program.

Western news media have quoted unidentified U.S. officials as saying that a Sept. 6 Israeli airstrike hit a nuclear facility in Syria linked to North Korea. Syria has said an unused military building was hit.