A Chinese court has ordered two Japanese historians to pay damages of 1.6m yuan (£110,000) to a survivor of the Nanjing massacre after they accused her of fabricating her account of the 1937 atrocity.

Although the ruling will be impossible to enforce across national boundaries, the defamation lawsuit opens up a new front in a conflict over wartime history that has recently prompted a spate of trials, street demonstrations and a deterioration in relations between Asia's two most powerful nations.

The Nanjing court judged that Xia Shuqin suffered psychological trauma and damage to her reputation from two books published in Tokyo that denied large-scale slaughter took place in Nanjing, despite Chinese claims that 300,000 civilians were killed by the Japanese imperial army.

The authors, Shudo Higashinakano and Toshio Matsumura, claimed in their studies that key testimonies by Ms Xia - who was eight years old in 1937 - and another survivor, Li Xiuying, were faked.

As well as validating Xia's account and awarding compensation, the court ordered the publisher, Tendensha, to stop printing the books and withdraw and destroy all copies that had already been distributed.

It said the authors and publishers must pay for a public apology to be carried in prominent Chinese and Japanese newspapers.

Chinese courts have no jurisdiction in Japan so the verdict is largely symbolic. The Japanese defendants, who were not present at any of the hearings, rejected the result.

The managing director of Tendensha, Takayuki Fujimoto, said in a statement: "We feel suspicious of the politically motivated attempt to obliterate genuine academic research into a historical event. This is a challenge to our country's freedom of speech in the guise of a trial. It is nothing more than meddling."

For most of the postwar era, the most widely accepted death toll was calculated by the Tokyo War Crimes Tribunal, which estimated 142,000 civilians and prisoners of war were killed in and around Nanjing. But in recent years, this figure has been challenged by revisionists on both sides.

Japanese nationalists have argued that the Allied-controlled tribunal grossly exaggerated the slaughter, which they said was nothing more than that of any major battle. Chinese scholars - notably Iris Chang - have claimed that the death toll was twice as high as western scholars believed.

Legal attempts to seek compensation for wartime atrocities have usually been launched in Japanese courts. There have been only a tiny number of successful lawsuits, many of which were later overturned on appeal, prompting accusations that the judiciary in Tokyo lack independence.

China's legal system is even less transparent and independent. But supporters of the victims say this case is significant as it is the first war-related defamation lawsuit

"This verdict is a warning to Japan's right wing that they must not deny the massacre took place", said Zhang Lianhong, director of Nanjing Normal University's Massacre Research Centre. "It is a legal validation of Xia's testimony and it should help to ease the pain that she felt when her account was disputed."