The United States and its allies South Korea and Japan will boycott six-party talks in Beijing this week on North Korean denuclearization, reports the Japanese newspaper Asahi Shimbun.

Washington asserts it will not participate in any further talks unless North Korea shows its sincerity in resuming the diplomatic process by freezing its uranium enrichment program and allowing international nuclear inspections to resume at the Yongbyon nuclear site.

Meeting at the U.N. Wednesday, Japanese Prime Minister Yoshihiko Noda and South Korean President Lee Myung-bak concurred that they should cooperate in dealing with North Korea and to settle disputes between their two countries, The Korea Herald reported.

In a statement released by Lee's office, the president said South Korea and Japan acceded to a mutual understanding that abiding to the policy agreed by six nations in dealing with North Korea is a key factor not only for maintaining national security, but also for cultivating international peace and stability.

He also stated that the two countries agreed to collaborate on improving their relations in a "mature, future-oriented manner while facing up to past history."

The two leaders are currently attending the U.N. General Assembly in New York.

"I expect that Prime Minister Noda will contribute greatly to strengthening relations between the two countries," the South Korean president said in an introductory speech on the sidelines of the U.N. General Assembly.

The Japanese leader responded by emphasizing that continuity is vital to diplomacy and his government will regard South Korea as a very important neighbor as his predecessors did. He also vowed to persevere in strengthening their friendly relations. Among the measures that have been agreed upon is Japan's promise of returning centuries-old Korean royal texts.