NEW YORK — In response to privacy concerns, Google says it has tweaked Buzz, the social hub it added to its e-mail service this week.

Users worried that Buzz made their frequent e-mail contacts visible to others. And it did so by automatically making these contacts their followers and followees on Buzz, and making these lists public.

On Facebook, that would be like having the people you e-mail with most often automatically become "friends." But those people may instead be your boss or ex-lover, and you wouldn't necessarily want to share everything with them.

So Google Inc. said Thursday it made it easier to hide the lists of followers and followees. It also made it easier to block specific people from following your Buzz updates.