Diplomatic negotiations to restart the stalled six-party talks over North Korea's nuclear weapons programs continued Tuesday in Tokyo, but there was little visible progress as negotiators from five countries failed to persuade North Korea to come back to the table.

Meanwhile, the lead U.S. negotiator refused to hold a bilateral meeting with his North Korean counterpart, demanding that Pyongyang return to the multilateral talks without conditions.

Negotiators from the U.S., China, Russia, Japan and the two Koreas were in Tokyo, some of them to participate in a two-day security conference, and hoped to use the opportunity to revive the six-party talks.