Negotiators on North Korea's denuclearization confirmed Wednesday that they will press Pyongyang during next week's six-party talks to agree to verify its nuclear disarmament in writing.

U.S. Assistant Secretary of State Christopher Hill and his South Korean counterpart, Kim Sook, were in Tokyo to meet with Japan's top envoy, Akitaka Saiki, to lay the groundwork before the six-party talks, which also include North Korea, China and Russia, slated for Monday in Beijing.

"There must be a clear commitment in writing" on allowing inspectors to take samples from North Korean nuclear facilities, Saiki said after the meeting. "There can not be any misunderstanding regarding the verification procedures."