The Japan Coast Guard turned a Chinese fishing vessel away Monday after it illegally entered Japanese waters near a disputed island chain, a spokesman said.
The Chinese boat was found 20 km northwest of Uotsuri Island, one of five uninhabited islands claimed by both Tokyo and Beijing, said Akira Miyahira, a coast guard spokesman. Japan controls the islands, which it calls the Senkaku. China calls them the Diaoyu.
He said the Chinese boat entered the Japanese waters illegally and it was not immediately known whether it was there to fish or make a statement about the territorial dispute. After the coast guard issued a warning, the Chinese boat left Japanese waters.
The islands are a source of friction between Japan and China. Japan says it has controlled the islands since defeating China in a war more than a century ago, but China says it had sovereignty over the islands centuries before Japan claimed control.
In March, Japanese authorities arrested seven Chinese activists and deported them after they landed on one of the islands to protest Tokyo's control.
Boatloads of activists from China and Taiwan periodically try to visit the chain but are usually kept back by the coast guard.