The six-party nuclear talks are not likely to be held this week, as Pyongyang has not yet fully disclosed its nuclear programs.

North Korea has agreed to declare all of its nuclear activities under a series of six-way denuclearization accords, the latest of which was reached in October.

Japanese Vice Foreign Minister Shotaro Yachi on Tuesday dismissed the possibility the next six-party meeting would start Thursday as scheduled, as the U.S. has just launched talks with North Korea in Pyongyang.

On Monday, top U.S. nuclear envoy Christopher Hill flew to Pyongyang for direct dialogue with North Korean Vice Foreign Minister Kim Kye-kwan.

Prior to Yachi's remarks, Hill said that China is preparing to host the six-party nuclear talks late this week.