The Soviet Union sought to settle a territorial dispute with Japan in 1972 by handing over two of four disputed islands off Hokkaido in response to improving China-Japan relations, declassified documents obtained by Kyodo News showed Sunday.

It is the first time it has come to light that the Soviet Union's wariness about the normalization of diplomatic ties between China and Japan prompted Moscow to seek resolution of the territorial dispute with Tokyo and thus the conclusion of a postwar peace treaty, according to experts in Japan and Russia.

A series of formerly classified documents, including a draft peace treaty, were drawn up when the Political Bureau of the Central Committee of the Communist Party of the Soviet Union discussed measures to improve relations with Japan on Aug. 3, 1972.