The top U.S. nuclear envoy says technical discussions on shutting down North Korea's nuclear program have made progress, but notes that more work is needed.

During a second day of six-nation meetings in China's northeastern city of Shenyang Friday, U.S. Assistant Secretary of State Christopher Hill said there is a lot more to discuss before the parties can reach a common understanding on North Korea's disarmament.

The talks are expected to lay the groundwork for a September meeting of the six countries - North and South Korea, China, Japan, Russia, and the United States.

Last February, North Korea pledged to provide details of all of its nuclear programs, and to eventually dismantle them.

A confidential report from the United Nation's top nuclear watchdog, the International Atomic Energy Agency, leaked to the media Friday, says Pyongyang is living up to that promise.

The report says IAEA experts have been allowed to examine and verify the shutdown of North Korea's main Yongbyon nuclear facility.

North Korea closed its main nuclear facility last month and allowed nuclear inspectors to return to the country after barring them for nearly five years.

In return, Pyongyang received fuel oil from South Korea.

Pyongyang has been offered further fuel aid and diplomatic concessions from other nations if it ends all nuclear activities, and fully reveals its nuclear stock.

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