A powerful artwork, responding to the terrorist attack on the French magazine Charlie Hebdo, has been widely attributed to the secretive street artist Banksy but is actually the work of another artist, according to reports.

The image was initially shared on Instagram on Wednesday night, and went on to be shared over 100,000 times on various social media platforms. It shows three views of a single pencil, one intact, one snapped in half and one with the back half-sharpened, so it comprises two pencils.

A spokesperson for the elusive artist, however, told the UK's Independent that the image was not his work. "We can confirm this is not by Banksy," the artist's representative said.

The image is reportedly the work of London-based graphic designer and artist Lucille Clerc, who posted the image without a filter an hour before it appeared on the fake Banksy Instagram account, according to Yahoo News.

Clerc does not appear to be upset that her work was so widely attributed to another artist. In an email to Mashable, she said: “This is irrelevant. … There are way more important things to talk about at the moment, and in the end what matters is that this image speaks to people, so the more it spreads the better it is.”

More of Clerc's work can be viewed on her Instagram page.

Wednesday's attack against the offices of Charlie Hebdo, a French satirical magazine, resulted in the killing of 10 staffers and two police officers. The magazine is famous for its sometimes controversial cartoons, which include images of the Prophet Muhammad, which are forbidden in some Islamic sects.

Four famous French political cartoonists -- Jean Cabu, Stephane "Charb" Charbonnier, Bernard "Tignous" Verlhac and Bernard Maris -- were among those killed in the attack.

Two of the suspects, brothers Saïd and Chérif Kouachi are still at large, and are believed to have trained with al Qaeda. Hamyd Mourad, who was also wanted in connection with the attack, turned himself in to French police Thursday.