The historians, 10 from each side, reached the agreement after two days of talks in Tokyo, part of the two countries' efforts to improve ties often strained by disputes over the past.

"We want to avoid the studies ending up with both sides just expressing their views, so we agreed on the need to look into some common issues," said Shinichi Kitaoka, a professor at the University of Tokyo who heads the Japanese group.

He told a news conference that the two sides also agreed their studies would look into how history is viewed and taught in each country.

This year marks the 70th anniversary of the Nanjing Massacre and the Marco Polo Bridge incident that led to full-scale war between Japan and China.

Some Japanese historians say the 1937 massacre in Nanjing has been exaggerated, but China says the barbarity of the event is a fact and puts the death toll at 300,000. An Allied tribunal after World War Two estimated that around 142,000 were killed.

Sino-Japanese relations were icy for much of the past half-decade, largely because of former Prime Minister Junichiro Koizumi's annual visits to the Tokyo Yasukuni shrine to war dead, which is seen by Beijing as a symbol of Japan's past militarism as it also honours some convicted war criminals.

Koizumi's successor, Shinzo Abe, has tried to mend fences, visiting China in October just weeks after he took office and agreeing to the joint history study.

While Abe has more recently triggered a diplomatic furore with his remarks about wartime brothels run by the Japanese military, the issue was not among those the two sides agreed to specifically take up, Kitaoka said.

Abe said there is no proof that Japan's government or army forced women, mostly Asian, to serve Japanese soldiers in the brothels during World War Two.

With Chinese Premier Wen Jiabao set to visit Japan next month, Abe has sought to quell the uproar by repeating that a 1993 Japanese apology to the "comfort women" -- as they are known in Japan -- stood, and expressing sympathy for their suffering.

China has urged Japan to face up to its past, but has been restrained in its reaction to Abe's remarks.

The historians, who held their first meeting late last year, plan to meet twice a year and aim to come up with a report in June of 2008.

In addition to the contentious area of modern history, when Japan invaded and occupied parts of China from 1931 to 1945, the studies will also take up ancient and medieval history.