Five Chinese citizens seeking compensation from Japan for injuries from poison gas left behind in China by Japanese forces during World War Two lost a court battle on Tuesday.
The five Chinese had sought a total of 80 million yen (US$680,000) from the Japanese government for injuries and health problems they suffered between 1950 and 1987.

But on Tuesday, the Tokyo High Court upheld a lower court ruling in May 2003 that had dismissed their damages suit, one of a range of war-related issues that have at times strained relations between the two Asian giants.

It was not immediately clear whether the Chinese plaintiffs would appeal to the Supreme Court.

Beijing and Tokyo have been grappling with a number of disputes over everything from energy resources and territorial boundaries to historical issues stemming from Japan's invasion and occupation of parts of China from 1931 to 1945.

But ties have warmed since Japanese Prime Minister Shinzo Abe took office last September and made his first trip abroad an ice-breaking visit to China. Chinese Premier Wen Jiabao is expected to make a reciprocal visit to Tokyo in April.

In a separate but similar court battle, the Tokyo District Court ordered the government in September 2003 to pay a total of about 190 million yen in compensation to 13 Chinese, including bereaved relatives of victims.

The Japanese government filed an appeal several days later.

The case arose from poison gas incidents in 1974 and 1982 and a shell explosion in 1995, all involving discarded Japanese munitions in Heilongjiang province in northeastern China.

China says Japanese forces left behind about 2 million chemical weapon shells in China, and more than 2,000 people have been harmed by them.

Japanese studies have placed the number of such shells at about 700,000.

Japan had pledged to clean up the weapons by this year, but it later sought an extension, saying the deadline was impossible to meet. China has complained about the slow pace of disposals.

On Aug. 4, 2003, one man died and more than 40 people were injured after five World War Two-era metal barrels containing mustard gas were unearthed at a construction site in the city of Qiqihaer, Heilongjiang.

Japan apologized and paid a total of 300 million yen in compensation to the Chinese government for the Qiqihaer incident.