TOKYO - Senior officials of Japan and China agreed on Tuesday to pursue high-level dialogue to mend frayed relations, a Japanese government official said.Sino-Japanese ties, long plagued by conflicting claims to an East China Sea group of islands and by the legacy of Japan's World War Two aggression against China, have thawed somewhat since Japanese Prime Minister Shinzo Abe's meeting with Chinese President Xi Jinping in November 2014.But China's successful bid last week to include documents related to the 1937 Nanjing Massacre in a program by the UN cultural and heritage agency UNESCO has become a new irritant.Yang Jiechi, China's top diplomat, and Shotaro Yachi, the head of the secretariat of Japan's National Security Council, agreed in Tokyo to press ahead with bilateral dialogue including one between top leaders, the Japanese official said."There still exist some issues between the two countries like the East China Sea situation. But I would like us to exchange views candidly today to advance bilateral relations further," Yachi told Yang before doors were closed to reporters.Issues discussed include overall ties between Asia's two biggest economies, their security policies and a continuing effort to set up an emergency communication mechanism between their militaries, the official said. He declined to elaborate.Yachi, also a national security adviser to Abe, reiterated in the Tokyo meeting Japan's stance regarding China's move to have documents touching on the Nanjing Massacre registered in UNESCO's "Memory of the World" program, the official said.China says invading Japanese troops killed 300,000 people in the massacre. A post-war Allied tribunal put the death toll at about half that number."Japan's top government spokesman said earlier on Tuesday that Tokyo might halt funding for UNESCO over the UN heritage body's decision to include the documents. This drew a sharp retort from China, which called the threat "shocking and unacceptable".