The United States and North Korea held "a good discussion" on Tuesday over the communist state's nuclear disarmament, a top US envoy said, hinting at progress in resolving an impasse.
Going into the Singapore talks with North Korea's Kim Kye-Gwan, Hill had warned that "we are kind of running out of time" to resolve the impasse.
But on Tuesday night Hill said, "I think they do understand" the desire for a quick resolution.
"We will not be announcing any agreement of any kind here in Singapore but, if all goes well, I hope we can have some further statements in Beijing tomorrow, which would involve some follow-on activity."
He had last met Kim in Geneva in March, and called that meeting "very good". Results of the Singapore meeting were even better, he said.
"I would say we took the discussion beyond where we had it in Geneva," Hill said.
"I'm leaving Singapore with a feeling that we did as much as we could... I think it's been a good day in Singapore."
After briefing the reporters, Hill was to fly to Beijing for consultations with China and other members of the six-nation forum involved in talks on Pyongyang's nuclear programmes. Washington has been pushing North Korea to come clean on its entire nuclear programme as a key step in a 2007 six-nation denuclearisation deal that also involves China, Japan, Russia and South Korea.
The 2007 six-party deal grants North Korea - which tested an atomic weapon in 2006 - energy aid and major diplomatic and security benefits in return for full denuclearisation. The current phase of the deal required the North to disable its main plutonium-producing plants and declare all nuclear activities by the end of last year.
The North says it submitted the declaration in November. But the United States says it has not accounted for an alleged secret uranium enrichment programme or for alleged proliferation to Syria. South Korean media reports suggested that Kim might have been ready to hand over a document in Singapore that addresses concerns about the North's alleged secret uranium enrichment programme and co-operation with Syria.
South Korea's Hankyoreh daily said the US had vowed not to make public the so-called "confidential minute" or exploit it for political purposes.
"I don't want to get into specifics, but I assure you that we discussed all issues," Hill said.
The talks coincided with increasing tensions between Seoul and Pyongyang. Lee Myung-Bak, a conservative who took office as South Korea's new president in February, has angered the North by adopting a tougher line on ties.
"I hope the talks will be a success, paving the way for the settlement of the North Korean nuclear problem," Lee said in Seoul before a cabinet meeting.
"We will make efforts to improve inter-Korean ties but the six-party talks must also be successful."
Last week North Korea announced it was suspending all dialogue with the South and closing the border to Seoul officials. (AFP)
US reports 'good discussion' with N Korea over nuclear impasse