Angelina Jolie's father only found out she'd undergone a double mastectomy online.

The Salt actress opened up about her operation - which she decided to have after tests showed she carries the BRCA1 gene and had an 87 per cent chance of developing breast cancer and a 50 per cent chance of contracting ovarian cancer - in a moving piece in the New York Times newspaper, and Jon Voight has admitted he has only just learned the shocking news, despite seeing his daughter and her fiance Brad Pitt just two days ago.

"My love and admiration for my daughter can't be explained in words. I saw her two days ago with my son Jamie. We all got together for his birthday, with her and Brad. But I didn't know. It wasn't obvious at all. I found out this morning. I was as surprised as anyone and deeply moved by the way she's handled this. She's a very extraordinary person, the way she examined it and what she shared," he told the New York Daily News newspaper.

Jon, 74, insists he "absolutely" respects Angelina - who raises six children with Brad - for keeping her decision private during the three months of procedures and is grateful she has now taken the time to "educate" him: ''I completely understand, I want the focus to be on the inspiration. She just explained to me and educated me on this stuff."