A group of almost 40 Chinese citizens filed suit in a Beijing court Wednesday demanding compensation from two Japanese companies for forced wartime labour, their lawyer said.

Attorney Kang Jian said the suit, filed at the Beijing No. 1 Intermediate Court, involved two survivors and 35 people whose relatives were forced labourers.

The move comes in defiance of Japanese court and government pronouncements that such cases are blocked by international agreement, and with relations between Beijing and Tokyo in a deep chill.

Previous attempts to bring such cases in China have failed but Kang told AFP: "I don't think they have any reason not to accept the lawsuit."

The submission was widely covered by official Chinese media. State-run CCTV television identified one of the companies as Mitsubishi Materials Corp, as did Japan's Kyodo news agency.

CCTV also said the suit is seeking apologies printed in 17 Chinese and Japanese newspapers including the People's Daily and the Asahi Shimbun, as well as one million yuan ($163,000) in compensation for each worker.

Tens of thousands of Chinese were forcibly sent to Japan to work in factories and mines to fill a manpower breach arising from Japan's massive World War II military mobilisation. Japan had invaded China during the 1930s and the Asian mainland was a major front in the broader global conflict.

Japanese courts have rejected numerous similar cases filed there over the years, with the country's Supreme Court ruling in 2007 that individual Chinese cannot demand compensation from Japan.

The court said China gave up its right to make such claims when the countries normalised relations more than four decades ago.

The Japanese government reiterated that on Wednesday.

"As for the issue of the right to make claims related to the war, including for individuals, this right has not existed since the Japan-China Joint Communique" of 1972, said Chief Cabinet Secretary Yoshihide Suga.

The suit comes amid steadily worsening relations between Beijing and Tokyo due to a row over disputed islands in the East China Sea controlled by Japan and claimed by China.

Persistent tensions over how to interpret Japan's militarist and colonialist past in Asia have also soured relations between the world's second- and third-largest economies.

Chinese foreign ministry spokeswoman Hua Chunying said the documents agreed in 1972 were "the cornerstone for the development of China-Japan relations".

But she also criticised Tokyo. "The forced recruitment and enslavement of labour is a severe crime committed by Japanese militarism during its war of aggression and colonial rule," she said.

"We believe that the relevant Chinese court will deal with the lawsuit in accordance with law."