Negotiators trying to move forward with disarming North Korea made progress during a second day of talks on Friday on agreeing methods to verify the North's own account of its nuclear activities, an official said.

The South Korean official said there was not yet complete agreement, but that talks had moved beyond a discussion of a guideline for verifying North Korea's declaration to economic and energy aid for the impoverished and isolated nation.

"They started off with more discussions on verification and managed to bring their views together," the official told reporters of Friday's negotiating session.

"Does it mean they have an agreement? Well you can't quite say that, because they're looking at a package of agenda items."

The negotiators, from North and South Korea, the United States, Japan, Russia and host China, are seeking to push forward a preliminary disarmament deal that saw Pyongyang freeze and begin disabling its Yongbyon nuclear reactor.

In exchange for those steps, and for handing over last month the declaration originally due at the end of 2007, North Korea will receive much-needed energy aid and the promise of improved diplomatic relations.

But questions remain about the ambitions of North Korea, which defied international warnings by testing a nuclear device in 2006.

In particular, Washington suspects that the North was secretly trying to enrich uranium, another path to making material for nuclear weapons.

Chief U.S. envoy Christopher Hill has hinted that disagreement remained among the six countries over whether the declaration was adequate. Negotiators have also said there was discord over the specifics of how to verify the North's statement.

But at the first round of talks in nine months, envoys appeared upbeat, and the South Korean official described the North's chief negotiator, Kim Kye-gwan, as relaxed and making jokes during their initial session on Thursday.

The negotiating session is expected to end on Saturday.