Delegation heads to the talks, which involve China, the United States, the Democratic People's Republic of Korea (DPRK), the Republic of Korea (ROK), Russia and Japan, held a meeting on Friday, discussing the plan to disable the DPRK's nuclear facilities.

A series of bilateral meetings were also held on Friday, according to Qin Gang, spokesman of the Chinese delegation.

U.S. envoy Christopher Hill said Friday evening that negotiators "have made a lot of progress in discussing a lot of very technical complex issues."

"For me it is a very useful day because we were able to discuss some real specifics" including the scope of the disablement, he said, adding the negotiators were "into a stage of this process beyond anything that's been done before."

He said a road map for steps in the second phase of DPRK's denuclearization is necessary, and negotiators "were discussing real elements of what the road map would look like."

However, he said "we might not go with a joint statement" since it might be too time-consuming.

So far, no draft of an expected joint statement has been released while the meeting that began on Thursday has only two days to go.

"It's quite possible that the talks can end on schedule with a chairman's statement, but no draft for a joint statement has been distributed to us so far," Russian chief negotiator Alexander Losyukov told reporters Friday afternoon.

The solution of the issue will be a complicated process and it is not easy for the parties involved to reach agreements, he said, adding he believes finishing the denuclearization process within the year would be very hard.

Japanese chief negotiator Kenichiro Sasae said Friday afternoon that there was still major differences between concerned parties.

The Japanese and DPRK delegations held a 45-minute bilateral meeting, discussing the nuclear issue and bilateral relations.

"The two sides agreed to continue to hold a working group meeting (on the Japan-DPRK relationship), to make efforts for resolving the pending issues with common concern, including the history and the abduction issues," said Sasae.

ROK top negotiator Chun Yung-woo said all problems under discussion were interwoven and it's hard to say which one was the focal point of Friday's talks.

According to Hill, the DPRK has given the other delegations a date when they could first see the declaration of its nuclear programs, but he refused to reveal the date.

Negotiators signed a landmark agreement on Feb. 13 when they finished the fifth round of the six-party talks.

The DPRK must declare all nuclear programs and disable all existing nuclear facilities, while the other parties must provide a total of 1 million tons of heavy fuel oil or equivalent aid to the DPRK, according to the agreement.

The first phase of the sixth round of talks was held in March, which ended with a chairman's statement.