The top U.S. nuclear envoy says he had a very good meeting with his North Korean counterpart in Geneva about efforts to disable Pyongyang's nuclear weapons program.

Speaking with reporters Friday as he prepared to leave the Swiss city, U.S. Assistant Secretary of State Christopher Hill said the talks brought progress. But, he did not report any breakthrough on Pyongyang's delayed nuclear declaration.

Hill and North Korean envoy Kim Kye Kwan held two closed-door meetings Thursday in Geneva.

There are no plans for talks to continue Friday.

Prior to Thursday's talks, Hill said the U.S. is willing to be flexible on the format Pyongyang uses to provide a promised nuclear declaration. Hill stressed, however, that North Korea must prepare a complete and correct declaration of its nuclear activities.

The United States is demanding that North Korea account for uranium enrichment that it has never publicly acknowledged.

Hill has said he would offer ideas at the meeting to jump-start negotiations, but has not given any details.

Under a six-nation deal, Pyongyang was supposed to provide a list of all of its nuclear programs by the end of last year, but Washington says the list was not complete.

The six-party talks, which include the U.S., China, Japan, Russia and North and South Korea, began five years ago in an effort to get Pyongyang to end its nuclear weapons program in exchange for diplomatic benefits and energy aid.

Some information for this report was provided by AFP and Reuters.