Actors David Boreanaz, Olivia Wilde and Zach Braff have taken aim at bosses behind America's National Rifle Association (Nra) over their controversial new advert, with the Bones star blasting the online clip as "repugnant and cowardly".

Gun control has been a hot topic in the U.S. following the Connecticut school massacre which left 20 young children and six teachers dead last month (Dec12), and on Wednesday (16Jan13) President Barack Obama announced plans to tighten firearms regulations in a bid to prevent future tragedies.

Among the draft proposals are plans to ban automatic weapons and introduce universal background checks for all firearms buyers, but Nra bosses responded with a new video hailing Obama as an "elitist hypocrite".

In the clip, Obama is criticised for giving his daughters Secret Service protection, with a narrator asking, "Are the president's kids more important than yours? Then why is he skeptical about putting armed security in our schools when his kids are protected by armed guards at their school?"

The video has sparked outrage, and many celebrities have taken to their pages to slam the Nra.

In a post, Boreanaz ‏writes, "Nra is repugnant and cowardly with this web ad. Shame on you", while Wilde ‏rages, "I would like to take this opportunity to tell the Nra to go f**k themselves."

Country star Chely Wright ‏adds, "The Nra's newest ad is disgusting, in my opinion. They suggest that the President cares only for his kids. Shameful", and Braff muses, "This is not an Snl (Saturday Night Live) skit. This is a real Nra Ad."