Hackers claim to have acquired a database containing hundreds of thousands of photos that were sent using the popular photo and video sharing service Snapchat, and are threatening to release them on the internet.
According to reports, the pictures were obtained via a third-party consumer website or app that can store images exchanged via Snapchat.
Messages sent using Snapchat can be set to automatically delete after a number of seconds.
This feature has made it a popular communication service, particularly among young people, with half of its users aged between 13 and 17.
Because of the young age profile of Snapchat users, there are concerns that many of the hacked pictures could be of minors.
Also a cause of concern is that the service has developed a reputation as being used for so called "sexting" - where some users exchange explicit pictures with each other.
Snapchat, which itself has been subject to hack attacks in the past, says its servers have not been breached and were not the source of the leak.
So far, the file containing the pictures does not appear to have been published online.
However, Business Insider has reported that users of 4chan, the forum which recently published nude photos of celebrities that were obtained through hacking, say they have the file and are currently compiling the pictures into a database searchable by Snapchat username.