Hefner separated from ex-fiancée Crystal Harris last week when she called off their engagement just days before the wedding was scheduled to take place
Hefner told two followers on his Twitter account: "Anna is Crystal's best friend & mine as well. She's the one who helped me survive this past week. She's the best (sic)."
Recent reports suggested that Hefner had begun romancing Berglund following Harris's departure. He has yet to confirm or deny the speculation, although he appeared to play down the rumours by tweeting that he was "happy" to be single on Monday.
Hefner also retweeted messages between Berglund, who was Playboy Playmate of the Month for January 2011, and Harris expressing their excitement at seeing each other at the weekend.
Harris returned to the Playboy Mansion to visit 85-year-old Hefner on Father's Day, returning his dog Charlie which she had apparently taken in the aftermath of their split. She spent what would have been their wedding day at a pool party in Las Vegas.
Hefner also clarified reports that his ex-girlfriends Karissa and Kristina Shannon had returned to the mansion, telling Twitter followers that the twins are "staying in the Bunny House for a few weeks" until they find their own apartment.
> Hugh Hefner: 'I didn't see Crystal Harris split coming'