President Xi Jinping is expected to attend the first national memorial day for the Nanking massacre on Saturday, as China marks a deeply symbolic anniversary while it tries to improve ties with its old foe Japan. China consistently reminds its people of the 1937 massacre in which it says Japanese troops killed 300,000 people in its then capital. A post-war Allied tribunal put the death toll at 142,000, but some conservative Japanese politicians and scholars deny a massacre took place. Relations have deteriorated sharply over the past year after Japanese Prime Minister Shinzo Abe's visit to the Yasukuni Shrine honouring war criminals among Japan's war dead. The neighbours are also locked in a dispute over the Diaoyu Islands in the East China Sea, which Japan controls and calls the Senkakus. But both countries, mindful of the economic stakes, reached agreement last month to try to reset ties. Xi, who met Abe in Beijing in November, is expected to attend the memorial in Nanjing, diplomatic sources said. He will have to tread a fine line between reminding Japan of what happened and not derailing the thaw in ties. "They don't want to work things up," a Beijing-based diplomat said. "China wants to appear conciliatory while also not forgetting the past." Former Chinese foreign minister Tang Jiaxuan, who heads a committee on improving relations with Japan, dispensed with the usual fiery words last week when talking about next year's 70th anniversary of the end of the second world war. That is not to suggest China will start playing down the massacre. In the days running up to the memorial, the government has been releasing accounts of the violence from its official archives. Xinhua carried excerpts from the diary of Nanjing teacher Cheng Ruifang, who recorded how Japanese soldiers "killed and raped at will, regardless of the victims' ages".