Anti-Israel activists have been spreading photographs of a wounded child who they claimed was a victim of Israeli air strikes, but who in fact died in an accident six years ago.
Some of those who shared the image have since acknowledged their mistake, but hundreds have continued to circulate it as proof of Israeli aggression.
The deception continued as rocket fire from Gaza into Israel went into its fourth day.
The photograph was originally posted on Twitter by Khulood Badawi, whose user name comes with the tag "long live Palestine". Alongside the picture, which shows a bloodied young girl being carried away by a man, she wrote: "Palestine is bleeding…another father killed by #Israel…another father carrying his child to a grave in #Gaza."
Ms Badawi, according to Honest Reporting, is a United Nations worker. A contact list shows her as an Information and Media Coordinator for the UN Office for the Coordination of Humanitarian Affairs.
It was also posted by Diana Alzeer, with the comment "Gaza under attack".
The post was spotted by Israeli Twitter user Avi Mayer, and it has since been determined that the image was a Reuters photograph taken in the aftermath of a fatal accident in 2006.
Ms Badawi has so far failed to acknowledge the mistake, while Ms Alzeer initially denied that it was a false image. However she later wrote: "Warning/Apology: Photo I tweeted earlier which has been circulated over FB turns out to be old photo of Raja Abu Sha'ban killed in Gaza 2006". She also complained on her blog of her experience with "Israeli propaganda".
Another user, Maissam Nablussi, also circulated on Facebook an image of a strike in Gaza which he incorrectly attributed as from this week. She claimed it showed "Gaza under attack today" but the photograph was actually taken at least three years ago. Mr Mayer wrote on Twitter: "There's something deeply disturbing about individuals who use old photos of kids killed in accidents to try and frame others. Sick, really."