He said a last-minute deal became increasingly likely after the envoys from China, the two Koreas, the US, Japan and Russia came together on Monday evening.
"After dinner, discussions gained pace rapidly to fine tune the wording of a joint document," the official said in reference to the hoped-for joint agreement that would outline North Korea's first steps towards disarmament.
"If they struck a deal over a joint document, it would require approval from their home governments, so it would be adopted as early as tomorrow [Tuesday]."
As the talks in Beijing entered their final scheduled day on Monday, the chief US envoy said the burden lay squarely with North Korea to determine whether any progress would be made.
"It is up to the North Koreans. We have put everything on the table," said Christopher Hill.
"We have offered a way forward on a number of issues. They just need to make a decision."
Hill's comments were echoed by the South Korean and Japanese envoys, both eager to see progress from the six-party process.
"North Korea is making a fool out of Bush and the Neocons. It is amazing that the more stubborn the North Koreans the more, they are rewarded by so many goodies"
B Humble, UK
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Kenichiro Sasae, the chief Japanese negotiator, said any possibility of an agreement "hangs greatly on the response, or final answer, that North Korea brings today".
South Korea, which has taken a more accommodating line towards the North, also stepped up pressure for a deal.
"There is no dissent among the chief delegates that we need to draw a conclusion, an outcome, today," said Chun Yung-woo, South Korea's assistant foreign minister.
The talks have stalled on disagreements over the energy assistance the North would get in return for disarming.
Hoping to secure a last minute deal, Chinese officials met separately with the North Korean and US delegations on Monday morning.
The US and North Korean envoys were then due to hold their own one-on-one talks.
|North Korea's nuclear programme has |
sparked protests in the South [Reuters]
Six party talks on disarming North Korea began in 2003, but have produced little other than a draft plan under which the North would agree to end its nuclear programme in return for energy aid and security guarantees.
However, implementing that plan, and its exact terms, have proved the sticking point and observers say there is a growing feeling that without agreement soon the six-party format will be doomed.
It is unclear how much energy North Korea has demanded in return for giving up its nuclear programme.
Japan's Kyodo News agency reported on Sunday that North Korea wanted 1 million tonnes of oil annually before disarming, and 2 million tonnes every year from then on.
The issue of US financial sanctions against the North – a previous obstacle to progress at the talks - do not appear to have proved an issue at the current round.
On Monday Japan's Asahi Shimbun newspaper reported the US had told North Korea last month that it was prepared to declare that $11 million held in frozen North Korean accounts was legitimately earned, and was not related to alleged counterfeiting and money laundering.
The move would allow the money to be released from accounts frozen after Washington first made the allegations in 2005.