Working out a Joint document remains to be the focus of all sides as the six-party talks on the Korean Peninsula stretched to the seventh day.

The six nations will continue their exchange of views on the draft of a joint document. But whether a meeting of delegation heads will be held is yet to be confirmed.

As of Monday, the fourth round of talks has already become the longest one sine the process was initiated in 2003. The date to conclude the talks remains unknown.

Chief negotiator of the Republic of Korea (ROK) Song Min-soon said Sunday it was hard to tell when the ongoing nuclear talks would end, but all sides agreed to establish a framework for the denuclearization of the Korean Peninsula.

The six delegations carried out discussions about the joint document draft at working-level during Sunday.

Sources quoted an official with the Russian delegation as saying that parties concerned had returned revised version of the draft back to China.

V. Yermolov, deputy head of the Russian delegation, was quoted by sources as saying that the revision of the draft is to enter "the final stage".