Japan has warned China of possible diplomatic fallout because of its seizure of a Japanese vessel over a pre-war debt.

The Japanese vessel was seized at a Zhejiang port Saturday after the Shanghai Maritime Court ruled in favor of the Chinese plaintiffs' claim for reparation on unpaid debts incurred by a Japanese shipping firm before World War II.

Like Us on Facebook

The case history dates back to some 80 years ago when a Japanese shipping firm operating in the 1930s rented two Chinese ships from Zhongwei Shipping Company under a one year contract.

But the two rented Chinese ships were used by Japan's Imperial Navy during the war and had sunk.

The 1930s Japanese shipping firm which rented the two Chinese ships had since merged with a new company, which merged with yet another company until Mitsui OSK Lines, owner of the impounded vessel, was formed.

In 2007, the descendants of Zhongwei Shipping's founder filed for a compensation suit against Mitsui.

The lawsuit has resulted to the Shanghai court ordering Mitsui to pay a hefty compensation of CNY 2.9 billion, according to Reuters.

According to Japan's representative Yoshihide Suga, the seizure of their vessel has breached a 1972 agreement in which China had already waived war reparation demands from Japan.

Suga expressed Japan's worry over the possible harm that the seizure could do to the two countries' diplomatic relations, and hopes that China would take steps to remedy the issue.