Police have decided to ask China to help in the investigation of a Chinese man allegedly involved in fabricating alien registration cards in Japan, sources said Saturday.

The man, who is in his 30s and currently lives in China's Fujian Province, is suspected of teaching techniques for fabricating the cards. The recipient of this knowledge, also Chinese, is under arrest in Japan for allegedly masterminding a series of card forgery cases, the sources said.

The Aichi Prefectural Police will dispatch officers to China as early as next month, the sources said.

According to investigations, Liu Bing, the man under arrest, and his accomplices sold about 3,700 fake documents including alien registration cards and driver's licenses to people from about 40 countries who are in Japan illegally, making about 100 million yen.