"The parties evaluated progress made toward an agreement on terms for verification," said a chairman's statement issued at the end of the talks.

How to verify the declaration of the Democratic People's Republic of Korea's (DPRK) nuclear program was the sticking point in the latest round of talks, which started on Monday.

After four days of intensive one-on-one and plenary meetings, the six parties failed to reach an agreement on a verification draft, in which host China put together the views of all parties.

Under an agreement reached at the talks in February 2007, the DPRK agreed to abandon all nuclear weapons and programs. It also promised to declare all its nuclear programs and facilities by the end of 2007. In return, the DPRK would get diplomatic and economic incentives.

"Through days of discussions, the six parties came to some consensus, but remained apart on some issues," Foreign Minister Yang Jiechi said in a meeting of the six chief negotiators earlier yesterday.

Yang called for all parties to remain confident and patient, show wisdom and the utmost flexibility as a way of moving forward the talks.

"We were not able to get an agreed verification protocol," US negotiator Christopher Hill said at the Beijing airport before leaving China, according to the Republic of Korea (ROK)'s Yonhap news agency.

Yonhap also cited ROK delegates as saying that the six nations involved in the talks - the DPRK, the ROK, China, the United States, Japan and Russia - had failed to agree on a draft protocol for verifying its nuclear information.

Hill added that the six parties would continue to try to set DPRK's verification commitments in writing, according to Japan's Kyodo news agency.

The on-again-off-again talks were initiated in 2003 and are aimed at denuclearizing the Korean Peninsula.

The latest round of talks also dealt with how to fully implement the second-phase action plan prescribed in the 2007 agreement as well as how to put forward a northeast Asian peace and security guiding principles.

Russia circulated a revised draft of guiding principles on peace and security to other parties.

According to the chairman's statement, a working group meeting under the Russian chairmanship will be held in Moscow in February 2009 to further discuss the principles.

The ROK, as the chair, would convene a working group meeting at an appropriate time to coordinate the assistance to the DPRK.

The six parties also agreed to "convene the next meeting as soon as possible".

The parties encouraged sincere efforts by the DPRK and the US, as well as the DPRK and Japan, toward normalizing their relations, said the statement.