A tentative deal to curtail North Korea's nuclear programme has been reached at six-party talks in Beijing.
Mr Hill said governments would look at a draft deal
US envoy Christopher Hill said intense negotiations had produced "an excellent draft" outlining various steps forward.
The deal is thought to focus on promises of energy aid to North Korea, in return for it beginning to disarm.
But the agreement still needs approval from each of the six nations involved, and Japan has already voiced doubts of it sticking.
The current round of six party talks - involving the US, China, Japan, Russia and the two Koreas - began on Thursday, with a renewed sense of optimism from all sides.
But negotiations quickly faltered, with disagreements over the amount of energy aid the North was demanding in exchange for disarming.
In a last-ditch attempt to reach agreement, delegates sat down for late-night discussions on Monday, and appear to have hammered out a deal.
Mr Hill said the tentative agreement had the support of the US government.
"Yes, we've approved it, to the best of my knowledge we've approved it," Mr Hill told the Associated Press.
He added that the North Koreans had also seen the same text and, according to the Chinese, they "went over every word of it".
There has been no official comment from the North Koreans, but South Korea's envoy Chun Yung-woo said he believed the proposal would be acceptable to Pyongyang.
"I am looking forward to hearing good news today," he told reporters on Tuesday.
So far, delegates have given few details of what this agreement entails, but Reuters news agency quotes a source close to the talks as saying the North would be given 50,000 tonnes of energy aid in return for shutting down its nuclear facilities, and more for "disabling" them completely.
N KOREA NUCLEAR PROGRAMME
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The New York Times added that the deal called for Pyongyang to complete the "permanent disablement" of its Yongbyon nuclear facilities within 60 days.
Mr Hill told reporters that a text of the agreement was now being referred to each government for approval.
But even if the deal is agreed by all six parties, it will only be the first step in the disarmament process.
"This is only one phase of denuclearisation. We're not done," said Mr Hill.
One of the topics that looks set to be left for later discussion is the fate of any nuclear weapons the North already possesses.
Even though the deal has yet to be officially agreed, criticism of it has already started.
John Bolton, former US ambassador to the United Nations, said North Korea should not be rewarded with "massive shipments of heavy fuel oil" for only partially dismantling its nuclear arsenal.
"It sends exactly the wrong signal to would-be proliferators around the world," Mr Bolton told CNN.
Japanese Foreign Minister Taro Aso told Kyodo news agency: "Whether (the deal) actually goes ahead remains to be seen. We do not know whether it will go ahead, just because it has been signed."
But analysts say that, despite the difficulties ahead, any deal reached at this stage would be a significant step forward in a process which has now been going on for more than three years, with little reward.
The most recent deal, in September 2005, rapidly fell apart over differences between North Korea and the US over implementation.
The North Korean nuclear issue has become even more pressing in recent months, after Pyongyang conducted its first nuclear test in October.