As the fourth round of six-nation talks on defusing the North Korean nuclear threat started Tuesday, Tokyo, as expected, reiterated its demand that Pyongyang resolve the issue over its abductions of Japanese.

Japan's chief negotiator, Kenichiro Sasae, director general of the Foreign Ministry's Asian and Oceanian Affairs Bureau, said getting North Korea to drop its nuclear arms and missile programs and come clean on the abductions are issues that must be comprehensively resolved before Tokyo can entertain establishing diplomatic relations with Pyongyang.

Tokyo hopes to discuss the abduction issue with Pyongyang bilaterally on the sidelines of the six-way talks, which involve the two Koreas, Japan, the United States, China and Russia.

North Korea has repeatedly voiced opposition to Japan raising the abductions during the multilateral discussions.

Japan has addressed the issue in past six-party talks as well as during bilateral talks with North Korea on the sidelines of the six-nation forum.

South Korean Deputy Foreign Minister Song Min Soon, South Korea's chief delegate to the talks in Beijing, again urged Japan on Tuesday not to raise the abduction issue.

He also urged the U.S. not to take up North Korea's human rights record.

"Discussions should be focused on the (nuclear) issue," Song said in the opening session of the fourth round of the six-nation talks, convened in the morning.

Differences between Japan and North Korea over the abduction issue have since 2002 prevented the two countries from normalizing diplomatic ties or even resuming talks to that end.