Hollywood Leaks has denied involvement in the Scarlett Johansson nude photo scandal. The group tweeted a denial on Monday afternoon amid mounting speculation that the Anonymous offshoot was a prime suspect in recent A-list cell phone photo leaks.

At about 3 p.m. Monday, the hackers tweeted the following message:

WE DID NOT LEAK THE SCARLETT JOHANSSON PICS, WE WOULD HAVE RELEASED IT HERE FIRST! So stop the speculating!

Indeed, the group has not been shy about taking credit for photo leaks in the past. Hollywood Leaks gleefully claimed responsibility for hacking the phone of Dancing With the Stars talent Julianne Hough and circulating photos of the star in late August.

The group explained its mission to Gawker earlier in August: We're simply here to facilitate the free flow of information from a place which was previously overlooked, Hollywood, an unidentified representative wrote in an email, prompting Gawker to tag them Wikileaks to the Stars.

But the Hollywood Leaks Twitter feed was silent on the hacked photos of Scarlett Johansson and Justin Timberlake (by way of Mila Kunis' phone).

On Wednesday, naked self-portraits of actress Scarlett Johansson began making the rounds on Twitter and other Web sites. Later that same day, an uninidentified person sent an email to Perez Hilton on Wednesday, offering to sell compromising photos of Justin Timberlake that he sent to his Friends with Benefits costar.

Johansson was outraged by the invasion of privacy, and enlisted the FBI to investigate.

The FBI is investigating a person or group responsible for a series of cyber intrusions of high profile figures, FBI spokeswoman Laura Eimiller told E! News last week. This would include many devices-could mean a computer, desktop, laptop, iPad, cell phone...intrusions into personal online accounts too.

The Los Angeles Times reported that the FBI probe had begun before Johansson's nude photos were leaked. And on Thursday, TMZ reported th FBI was closing in on the hacker.

If not Hollywood Leaks, then who?