The six-party talks, held between North Korea, the US, China, Japan, Russia and South Korea, are aimed at dismantling the North's nuclear programme.
In the September 2005 six-party talks accord, Pyongyang agreed in principle to scrap its nuclear weapons in exchange for aid and security guarantees.
The US wants to see evidence of North Korea's compliance.
Neil Richardson, the governor of New Mexico and a former UN ambassador, said after a meeting on Friday that he had pressed officials from North Korea's UN mission to invite UN weapons inspectors back to the country and shut down its nuclear reactor.
Richardson said: "What I believe is that the atmosphere is good for some progress, and that is a step in the right direction, because for 13 months there's been no progress."
He said that the North Koreans seemed ready for open dialogue. Vice foreign minister Kim called on Saturday for sanctions to be lifted before Pyongyang would abandon its nuclear weapons.
"There is no reason to give up our nuclear weapon now. To do so, it is a prerequisite to lift sanctions against us"
Kim Kye Gwan,
deputy foreign minister
He said: "There is no reason to give up our nuclear weapon now. To do so, it is a prerequisite to lift sanctions applied against us."
Condoleezza Rice, the US secretary of state, said in an interview with Reuters that UN sanctions imposed on Pyongyang as a result of the October nuclear weapons test would continue even if talks in Beijing showed progress.
But she indicated flexibility on other issues, including the frozen North Korean accounts at the Banco Delta Asia.
North Korea boycotted talks for more than a year after a US-led financial crackdown in November 2005 froze North Korean assets in the Macau-based bank.
Rice said: "We're not going to allow them to continue to violate our laws, but obviously we'll look at the totality of all of this and see where we are after the next couple of rounds."