A Japanese military brothel in China has been declared a protected historic site, state media said on Thursday, as Beijing highlights old grievances amid modern-day tensions with its longtime rival.
The seven-building complex in the eastern city of Nanjing housed more than 200 "comfort women" forced to serve Japanese soldiers during World War II, and was the largest such facility in Asia, the official news agency Xinhua reported.
The former Chinese capital had 40 such stations run by Japanese troops, it cited Nanjing Normal University historian Jing Shenghong as saying.
The designation comes as China seeks to increase attention on Japanese imperial aggression during the early 20th century, while at the same time acting more assertively over disputed islands in the East China Sea controlled by Tokyo.
Relations between the two Asian giants soured in 2012 when Tokyo nationalised a few of the long-disputed islands, known as Diaoyu in China and Senkaku in Japan.
Japan invaded China in the 1930s and the two countries fought a full-scale war from 1937 until Tokyo's defeat in World War II in 1945.
In February this year Beijing approved national remembrance days to commemorate Japan's defeat and the "Rape of Nanjing" -- six weeks starting in December 1937 in which Japanese soldiers rampaged across the city.
Chinese estimates of the dead run as high as 300,000, although some respected foreign academics put the number significantly lower.
Also in February Nanjing applied to UNESCO to include documents relating to the event in its Memory of the World Register.
In a court case with political overtones in April, a Shanghai court impounded a large Japanese freighter in a dispute dating to the 1930s until its owner paid $28 million in compensation.
Beijing's state-controlled media have compared Japan's democratically elected Prime Minister Shinzo Abe to Adolf Hitler, urging him to emulate Germany's post-war contrition for the evils of Nazism.
Tensions escalated again late last year when Abe visited the controversial Yasukuni shrine in Tokyo that honours Japan's war dead, including convicted war criminals.
Beijing has dispatched a large number of vessels to waters near the disputed East China Sea islands, prompting Japan to frequently scramble aircraft, raising fears of an unintended clash that could escalate.