TOKYO - The U.S. envoy to North Korean nuclear talks said on Wednesday there had been progress on disabling the North's atomic facilities under an international agreement.

But Assistant Secretary of State Christopher Hill would not say whether a deal could be clinched by year-end that would lead to Pyongyang's removal from a U.S. terrorist blacklist.

Hill is to meet North Korean counterpart Kim Kye-gwan and possibly other officials in Pyongyang on a December 3-5 visit, State Department spokeswoman Nancy Beck said earlier in Washington.

He will also travel to the North's nuclear establishment at Yongbyon to observe the disablement of a reactor there, and meet U.S. experts who aim to finish the job by the end of the year.

Countries seeking to push forward a multilateral disarmament pact agreed to in February have sent a joint team to Yongbyon to assess steps to cripple the nuclear complex.

"I think we are making progress and clearly we have more to do, but I think we are on schedule for getting to the end of the year and getting all our commitments done," Hill told reporters in Tokyo after meeting his Japanese counterpart, Kenichi Sasae.

Asked if Washington was likely to state its intention to take Pyongyang off a list of states that sponsor terrorism, Hill said:

"I think we have made some progress and I would expect all elements to move ahead by the end of the year, but I don't want to get into the specifics of it until we actually see where we are at the end of the year."

Exchanges between the United States and North Korea have increased since North Korea agreed in February to a six-way deal to freeze and then roll back its nuclear arms programme in return for massive aid and better international standing.

North Korea, which tested a nuclear device just one year ago, shut down its main reactor in July. In exchange for disabling its plutonium production facilities, the impoverished state will receive 1 million tons of heavy fuel oil or equivalent aid.

The North must also give a full accounting of its nuclear programmes, while Washington is to move towards taking North Korea off a U.S. list of states that sponsor terrorism.

Checking disablement will be the easy part of the trip but getting Pyongyang to come up with an inventory of programmes acceptable to the United States will be tougher, said Kim Sung-han, an expert on U.S.-Korea relations at Korea University.

Hill said the United States wanted to work with Pyongyang to avoid a "crisis where ... we accuse the DPRK (North Korea) of not providing full disclosure". He added: "We want to be able to share the same goal ... which is complete denuclearisation."

A round of six-party talks among North and South Korea, the United States, Japan, Russia and China is expected to take place in Beijing from December 6 to 8, but no official dates have been set.