North Korea and the United States appeared to be inching closer to a deal that would establish a schedule for Pyongyang to shut down and seal its main nuclear facilities within two months, The New York Times reported on Saturday.
The newspaper said that North Korea was expected to receive in return shipments of fuel oil from South Korea and talks over normalisation of relations with Washington.
But the top American envoy negotiating the deal cautioned that the two sides remained stuck on "one or two" small issues.
"Nothing is agreed unless everything is agreed," Assistant Secretary of State Christopher Hill is quoted by the paper as saying.
"So I just want to be careful about predicting success tomorrow."
But in Washington, officials at the White House and the State Department were preparing for a major announcement this weekend, and described the agreement as very different from the nuclear freeze that the Clinton administration negotiated in 1994, the report said.
"This is the Libya model," The Times quotes one senior administration official as saying, referring to Libya's decision in late 2003 to turn over all the equipment it had purchased from the secret nuclear network run by the Pakistani scientist, Abdul Qadeer Khan.
In that agreement, both the Libyans and the United States took a series of steps that rid the country of nuclear technology and ended its isolation.
It is still unclear exactly what sort of timeline North Korea would agree to, and how quickly it would turn over the plutonium it has produced, along with whatever weapons it may have built, the paper said.
In the past, the Bush administration has said it would never agree to the kind of "freeze" that former president Bill Clinton signed, because North Korea was not forced to give up its weapons fuel before it reaped rewards, the report said.
Administration officials say this agreement would be different, because the biggest benefits for the North would come only after it allowed in inspectors, sealed its facilities and began to give up its weapons, the Times noted.
But those steps will be difficult to monitor, in part because there is a dispute about how much nuclear material the North possesses, the report said.
In a second stage of the agreement, the North would be required to declare how much nuclear material it has on hand and where it is located, said The Times.
Presumably, that would include the uranium enrichment program that Khan has admitted helping the North start a decade ago, but which North Korea has denied, the report said.