LOS ANGELES, Calif. (KTLA) -- The FBI's investigation into claims that multiple Hollywood celebrities had their phones hacked goes back well beyond news reports last week that actress Scarlett Johanson's nude photos had been acquired through a phone hack, law enforcement sources told the Los Angeles Times.

The FBI is investigating "a series of computer intrusions" that targeted celebrities, including, apparently, pictures of a semi-naked Johansson allegedly hacked from her mobile phone.

Nude pictures of the 26-year-old "Iron Man 2" beauty surfaced on the internet Wednesday.

FBI spokeswoman Ari Dekofsky confirmed that the agency is investigating "a person or groups responsible for a series of computer intrusions of high-profile figures in Los Angeles."

The federal probe began in 2010 after allegations of people hacking into phones and computers belonging to several Hollywood celebrities, law enforcement sources told the Times. The probe is ongoing.

However she said that, "due to it being an ongoing investigation, we are not at liberty to confirm specific victims or a number of victims."

In March, there were reports that hackers managed to get private information belonging to 50 female celebrities, including Johansson.

Others included Vanessa Hudgens, Jessica Alba, Christina Aguilera, Ali Larter and Demi Lovato.

The photos of Johansson, show the 26 year-old actress in a towel with an exposed backside, while another shows her topless.

They were posted on several celebrity gossip websites.