Chinese and Japanese scholars on Wednesday finished the first in a planned series of historical study groups ordered by their governments amid fresh efforts to mend strained ties and reduce bitterness between the former World War II enemies.

Twenty academics — ten each from China and Japan — met in Beijing for two days focusing first on the basic format and dates of future talks, said Shinichi Kitaoka, a University of Tokyo professor and head of the Japanese delegation.

Kitoaka said the talks so far were "serious, frank and friendly" but that they had yet to delve into specific historical events such as the Nanjing Massacre — a particularly painful subject that the two sides have sharp differences on.

Nanjing suffered a rampage of murder, rape and looting by Japanese troops in 1937 that became known as "The Rape of Nanking," using the name by which the city was known in the West at that time.

Historians generally agree the Japanese army slaughtered at least 150,000 civilians and raped tens of thousands of women. China says that as many as 300,000 people were killed.