The Federal Bureau of Investigation (FBI) is now dealing with what is now being described as "one of the biggest celebrity privacy breaches in history".

The FBI said it is "addressing the matter" involving the hacked and now widely circulated nude and risqué photos of celebrities including Oscar winner Jennifer Lawrence and model Kate Upton, among several others. Many of the photos began appearing online over the weekend.

Shortly before the deluge of photos began, anonymous members of online message boards bragged about possessing nude pictures of female celebrities.

Not long after the exposure of the private photos, it was suggested numerous times that hackers "ripped" images from Apple Inc.'s online data storage service iCloud.

Apple has said it is "actively investigating" the alleged compromising of its service. "We take user privacy seriously," Apple spokesperson Nat Kerris told NBC News.

The technology giant, however, has not explained how the hackers could have come into possession of the photos.

It has been speculated in online discussions that the leaked pictures were stolen from storage accounts. Some say that the hackers used a tool called iBrute, which can be utilized to try different password combinations on Apple's Find My iPhone service until accounts are infiltrated.

When the accounts are broken into, hackers can then gain access to iCould passwords and, subsequently, images and other data stored in the accounts.

Previously, Apple allowed users to try as many password combinations as they could on the Find My iPhone service but has since limited the attempts to five.

The FBI said it is "aware of the allegations concerning computer intrusions and the unlawful release of material involving high profile individuals." "Any further comment would be inappropriate at this time," the bureau said.

Last year, a Florida man was sentenced to 10 years in prison for intruding accounts of celebrities including Scarlett Johansson and Mila Kunis and posting their private pictures online.