The seizure of a Japanese cargo ship by a Chinese court over compensation claims relating to the second world war could potentially expose Japanese companies to hundreds of millions of dollars in liability, although the lapse of time and the deaths of elderly plaintiffs would make pursuing such cases difficult.

In February, a Chinese court for the first time accepted a lawsuit brought by 40 former forced labourers against Mitsubishi Materials Co and Nippon Coke & Engineering Co, claiming damages of about $40m. A series of related cases marks a breakthrough for activists, forced for years to seek redress in Japan as Chinese courts refused to hear their cases.

At the weekend, the Shanghai Maritime Court ordered the seizure of a Japanese-flagged ore carrier at a deepwater port near the city, after negotiations stalled between Mitsui OSK, which owns the ship, and plaintiffs in a case first opened in 1990.