China marks the anniversary of the 1937 Nanjing massacre with President Xi Jinping scheduled to take part in the first national memorial day of the war atrocity on Saturday.

The wartime massacre -- a usual thorn in diplomatic relations between Tokyo and Beijing -- involves the killing by Japanese troops of about 300,000 Chinese in China's capital then.

Like Us on Facebook

An Allied war tribunal counted the death toll at some 142,000, but there are Japanese politicians and scholars who deny a massacre ever happened.

In March, Tokyo lodged a protest with Beijing over Chinese President Xi Jinping statements about the massacre while on a visit to Germany.

Ties between the two Asian economic giants were strained in the past year after Japanese Prime Minister Shinzo Abe visited the Yasukuni Shrine honoring Japan's war dead, including war criminals .

The two are also in a territorial row over rock formations in the East China Sea

But a thaw in relations between the countries was in sight after reaching an agreement last month to try to reset ties. Xi met Abe in Beijing in November.

He is expected to attend the memorial in Nanjing where he will have to walk a tightrope in reminding Japan of the massacre and not getting in the way of improving ties.

A Beijing diplomat said the two leaders do not want to work things up, adding China wants to appear conciliatory while not letting go of history.

A former Chinese foreign minister who chairs a committee to mend ties with Japan, dispensed with the usual fiery rhetoric last week in discussing next year's 70th anniversary of World War Two.

The minister said the 70th anniversary is an important chance for Japan to review how it looks on and appreciates history, to let go of its burden by owning up to and reflecting on history and to have real reconciliation with its Asian neighbors.