North Korea has told Russia that it will not allow its partners in six-party nuclear talks to take any samples from the reclusive country's nuclear facilities for the purpose of verifying Pyongyang's nuclear declaration, sources said on Thursday.

North Korean Foreign Minister Pak Ui Chun relayed the stance to his Russian counterpart Sergei Lavrov during their meeting in Moscow on October 15, the sources said.

North Korea's stance is a flat denial of the US State Department's announcement made October 11 saying Pyongyang had agreed to allow its six-way partners - China, South Korea, the United States, Japan and Russia - use for verification "scientific procedures, including sampling and forensic a activities."

After being informed of the stance by Russia, China, which chairs the six-party negotiations, turned cautious about convening a six-way heads-of-delegation meeting, the sources said.

At their next talks, the six-party chief delegates are to compile a document to cover the recent verbal agreement between US and North Korean negotiators on verification measures.

The US and North Korean negotiators have agreed not to clearly state in writing at the session their accord on taking samples from North Korea's nuclear facilities.

But other partners such as Japan are strongly demanding that sample-taking be included in the document as a central tool to bring about North Korea's denuclearization under strict verification.

According to the negotiation sources, Pak told Lavrov that Pyongyang will allow its partners access to its nuclear facilities, discuss additional documents on its nuclear programs and interview people related to the nuclear plans.

Pak was also quoted as saying North Korea's partners cannot bring outside the country any material they would find through the verification process.

The United States has been seeking to hold the next six-party chief delegates' talks by the end of November. Sung Kim, US special envoy to the six-party talks is expected to discuss Pak's remarks when he meets in New York today with Ri Gun, head of the North Korean Foreign Ministry's American affairs bureau.

The current second phase of denuclearization, which obliges Pyongyang to disable its nuclear facilities and declare all its nuclear programs, is to be followed by the third phase in which Pyongyang must give up all its fissile material.