Google Inc. is preparing to offer its high-speed fiber-optic Internet service in four new metro areas, the latest step in a careful expansion of the service.

Google will announce launches of Google Fiber in Atlanta, Charlotte, N.C., Raleigh-Durham, N.C. and Nashville, Tenn. in coming days, according to two people familiar with the situation.

Google recently sent invitations to local news organizations in those four metro areas to attend events this week, without identifying the subject. The Atlanta and Nashville events are scheduled for Tuesday, Raleigh and Charlotte on Wednesday and Durham Thursday, according to local news reports.

A Google spokeswoman declined to comment. Officials in the four areas didn't return requests for comment.

In February 2014, Google said it was considering building Fiber in nine new metro areas. The other cities are Salt Lake City, San Antonio, Phoenix, Portland, Ore. and San Jose, Calif. Google has told some officials in those cities that it hasn't ruled them out, and has yet to make a final decision.