Sienna Miller has told an inquiry into press standards that she accused her family and friends of selling stories to the media after journalists obtained intimate information about her by hacking her phone.
The Layer Cake actress told the Leveson Inquiry she felt "terrible" for even considering that those closest to her could betray her in this way.
She revealed she changed her phone number three times in three months after becoming concerned that personal details were finding their way into newspaper stories.
Having switched her number repeatedly, Sienna said she was "pretty convinced" the leaks couldn't be the result of phone hacking and so accused close friends and family of being the source.
The actress said a reporter found out about a particular "very private" piece of information which she'd only told to four people, including her mother.
"I am very lucky, I have a very tight group of friends and a very supportive family, and to this date no-one has ever sold a story on me," she said.
"But it was baffling how certain pieces of information kept coming out and the first initial steps I took were to change my mobile number. And then I changed it again and again, and I ended up changing it three times in three months."
"Naturally, having changed my number and being pretty convinced that it couldn't be as a result of hacking, I accused my friends and family of selling stories and they accused each other as well," she added.
"I feel terrible that I would even consider accusing people of betraying me like that, especially being people who I know would rather die than betray me."
Sienna described becoming "very scared and intensely paranoid" about media intrusion in her life - claiming every area of it was "under surveillance".