A foreign ministry spokesman, in a statement carried by Pyongyang's official Korean Central News Agency (KCNA), accused Washington of using the first round of six-party talks held in Beijing last month to try to disarm North Korea.

"This compels the DPRK (North Korea) to discard any interest or expectations for the talks," the spokesman said.

"As already clarified, the DPRK has not made any promise regarding the next round of six-way talks," he said.

The spokesman criticised the United States for demanding North Korea move first to scrap its nuclear program while rejecting the North's "bold proposal" for the denuclearisation of the Korean peninsula.

"The US demand that the DPRK dismantle its nuclear deterrent force first under this situation will only lead to a war. This is clearly evidenced by the Iraqi situation," he warned.

North Korea is taking "practical measures to steadily beef up its nuclear deterrent force as a just self-defensive means" to counter a US pre-emptive attack against the reclusive country, he said.

The statement came as top Japanese, US and South Korean officials met in Tokyo for a second day of informal talks to refine policy ahead of a possible new round of six-way talks.

The meeting brought together Washington's point man in dealings with North Korea, James Kelly, Mitoji Yabunaka, head of the Japanese foreign ministry's Asian and Oceanian affairs bureau, and South Korean Deputy Foreign Minister Lee Soo-Hyuck.

A Japanese diplomat said the three admitted growing confusion over the North's intentions.

"The situation regarding North Korea is so uncertain. We have been receiving various messages. Very generally speaking, we just don't know what to make of them," the official said.

North Korea blamed US hostility for the lack of concrete progress during the first round of talks -- also involving China and Russia -- which took place on August 27-29 in Beijing.

The talks ended without a tangible agreement, with the delegates agreeing to meet again but failing to fix a date.