North Korea could shut down its plutonium-producing reactor within three weeks and return to international talks next month, a top US nuclear envoy said. Russia, meanwhile, said disputed funds reached a North Korean account at a Russian bank on Saturday, clearing a key hurdle to implementing a February pact to dismantle the North's nuclear weapons programs. Christopher Hill, the chief US envoy to nuclear talks, said the next round of negotiations which also involve South Korea, Japan, China and Russia, could begin in early July, even before a full shutdown of the Yongbyon reactor. Hill said the reactor would be closed after North Korea and the UN's nuclear watchdog agree on how to monitor the process. UN inspectors are to arrive in North Korea on Tuesday. "We do expect this to be soon, probably within three weeks ... though I don't want to be pinned down on precisely the date," Hill told reporters in Tokyo on Saturday after briefing his Japanese counterpart, Kenichiro Sasae, on the outcome of a two-day surprise trip to the North Korean capital. North Korea's official Korean Central News Agency described talks with Hill as "comprehensive and productive." Hill's trip - the first by a high-ranking US official since 2002 - came amid growing optimism that North Korea may finally be ready to take concrete steps toward fulfilling a promise to dismantle its nuclear programs. Last week, North Korea invited inspectors from the International Atomic Energy Agency to discuss procedures for shutting down its Yongbyon reactor. The country expelled the UN nuclear inspectors in late 2002. The IAEA announced Friday that a delegation led by Olli Heinonen, the agency's deputy director general for safeguards, would arrive in Pyongyang on Tuesday for a five-day visit. Hill said he was happy the team was set to go, but cautioned that halting the reactor was just a first step. "Shutting down the reactor won't solve all our problems, but in order to solve our problems we need to make this beginning," he said. North Korean officials told Hill during his visit that they were prepared to shut down Yongbyon as called for in a disarmament agreement reached in February, under which North Korea pledged to close the reactor and allow in UN inspectors in exchange for energy aid, including 1 million tons of heavy fuel oil. North Korea was to have done that by mid-April, but delayed because of the financial dispute. Some US$25 million in North Korean funds was frozen at the Macau bank after it was blacklisted by the US for allegedly aiding North Korea in money laundering and counterfeiting. The funds were freed earlier this year, but only last week started to be transferred to a North Korean account at a Russian bank. Russia's Foreign Ministry said the transfer has been made.