OSAKA -- A 34-year-old American man has been indicted for attempting to extort money from a high school girl he met via an Internet service, prosecutors said Friday.

Martin Caleb Dominguez, a resident of Sakai, Osaka Prefecture, contacted the 17-year-old student in mid-September, saying he would teach her English, and asked her to go out with him, according to the indictment and investigation sources.

After the girl rejected his advances, Dominguez sent 51 messages in English by the end of September to her mobile phone e-mail facility, the sources said. In one of the messages, he demanded that she pay 30,000 yen or "risk getting injured," they said. The student notified Osaka police and the man was arrested Oct. 9.

Dominguez was hired as a part-time English instructor by a prefectural high school in April 1998, but his contract was terminated in mid-October after his arrest.