Eleven Chinese are suspected of illegally entering Japan before 1998 with false documents, passing themselves off as children of a war-displaced Japanese woman left behind in China, sources close to the case said Sunday.

The Chinese are suspected of claiming to be the children of a woman from Yasuoka, Nagano Prefecture, sometime before 1998, the sources said. Their whereabouts remain unknown.

The woman has already died in China, they said.

The suspected illegal entry came to light when the woman's real children, living in Heilongjiang Province, northeastern China, applied to visit Japan through the Chinese government.