Talks on Pyongyang's commitment to close its main nuclear reactor in exchange for energy aid were expected to gain momentum, the chief US nuclear negotiator said Thursday, after the US took steps that could lead to the unfreezing of North Korean funds held at a Macau bank.

The US Treasury announced in Washington it had wrapped up an investigation of a Macau bank that the United States accused of helping North Korea launder money from counterfeiting and other illegal activities.

The thorny financial case had upset the North Koreans, who indicated in talks Wednesday with the chief UN nuclear inspector that they were still on line to close the Yongbyon reactor within a month, as long as Washington meets its promise to drop financial sanctions.

"We'll be having some consultations, I'm sure, in really the hours and days ahead ... with the six-party process again getting going this weekend," US Assistant Secretary of State Christopher Hill told reporters Thursday.

The six parties -- the two Koreas, the United States, China, Russia and Japan -- agreed last month that North Korea would get energy aid and political concessions for closing the reactor.

International Atomic Energy Agency head Mohamed ElBaradei also offered an encouraging assessment of the month-old nuclear disarmament pact, saying North Korean officials told him they were "fully committed" to implementing the deal to shut the reactor and welcome back UN inspectors.

The officials said they were "ready to work with the agency to make sure that we monitor and verify the shutdown of the Yongbyon" nuclear reactor, ElBaradei told reporters after the first IAEA visit to North Korea since its inspectors were kicked out four years ago.

He added, however, the deal between the US, North Korea and four other countries was still "fragile."

The Yongbyon reactor is believed to have produced plutonium for North Korea's nuclear test blast on October 9.

North Korean officials told ElBaradei they were waiting for the United States to drop financial sanctions that included a freeze on overseas assets, he said.

A particularly sore spot for the North Korean government has been the freezing of accounts in a bank in Macau, which include what Washington says are more than US$25 million (euro18.96 million) in North Korean assets.

Washington said Wednesday it would order US banks to sever ties with Banco Delta Asia, a measure that could in fact help the bank by replacing the blanket allegations with a definitive and limited US restriction.

The US Treasury Department also is expected to help overseas regulators identify individual account holders' risk of involvement in illicit activities. This assessment could be used by Macau to release money that has been frozen.

An Australian diplomat who returned from Pyongyang on Thursday also said North Korea remained committed to the agreement.

"I heard nothing in my discussions with the North Korean officials to indicate they were backtracking from that (agreement) or seeking to impose new conditions," said Peter Baxter, head of the North Asia Division of the Australian Department of Foreign Affairs and Trade.

Japan, however, was more muted in its response, saying that it doubted the US move would bring about any breakthroughs in the nuclear weapons dispute.

"I do not think this will lead to any sudden change in direction," Chief Cabinet Secretary Yasuhisa Shiozaki said in Tokyo.

ElBaradei was to meet Chinese Vice Foreign Minister Wu Dawei on Thursday and Hill on Friday.

Three other lower-level meetings, as required by last month's agreement, will also be held this week before the heads of the six party delegations meet on Monday.

One of the meetings to start Thursday will look at what sort of energy aid North Korea will get, South Korean nuclear envoy Chun Yung-woo said.

The talks "are not aimed at reaching any special conclusion, but rather to hear what it is that North Korea wants and what the other countries can do to meet such North Korean requests," he said.