Singapore, Apr 8: The United States and North Korea held key talks in Singapore on Tuesday over the communist state's nuclear disarmament but the US warned efforts to resolve an impasse were running out of time.

US envoy Christopher Hill and North Korea's Kim Kye-Gwan began their talks at about 11:00 am (0300 GMT) at the United States embassy, a US official said.

"I will be discussing the fact that we are kind of running out of time," Hill told reporters at his hotel before heading to the meeting. "We're not looking for an agreement. I think we're looking to have a consultation on some of the issues that have kept us apart for several months and certainly I will be discussing them."

Hill's comments added further weight to statements he made after arriving in Singapore on Monday night from Indonesia.

"We can't afford any further delays here," he said then. "We do need to make some progress very soon."

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.

Asked Tuesday morning what he expected from the Singapore meeting, Hill said: "We've got a pretty open agenda... We will see how it goes." He hinted it could be a long session, saying: "We have a lot of hours today."