The National Rifle Association (NRA) has come in for a wave of criticism after launching a shooting game on iTunes almost a month to the day after one of the worst mass-shootings in U.S. history.

The NRA: Practice Range app has been given a 4+ rating, meaning children as young as four can play it as it contains "no objectionable material".

The apps' description on Apple's App Store, says it offers "a 3D shooting game that instills safe and responsible ownership through fun challenges and realistic simulations. It strikes the right balance of gaming and safety education, allowing you to enjoy the most authentic experience possible."

There's also a $0.99 upgrade available for the game which lets players turn their gun to a pistol grip Mossberg or a semi-automatic sniper rifle.

There have been widespread calls for gun law reform after 26 children and teachers died at Sandy Hook Elementary School in Newtown, Connecticut. The U.S. President Barack Obama is expected to announce gun control legislation later this week. However, the NRA is a fierce campaigner against tightening gun laws and has recently blamed video games for gun violence.

"Guns don't kill people. Video games, the media and Obama's budget kill people," NRA Executive Vice President Wayne LaPierre said at a Dec. 21 press conference where he addressed the tragedy at Sandy Hook, according to NBC. "There exists in this country, sadly, a callous, corrupt and corrupting shadow industry that sells and stows violence against its own people, through vicious, violent video games with names like 'Bulletstorm,' 'Grand Theft Auto,' 'Mortal Kombat' and 'Splatterhouse.'"

Not surprisingly, the apps release has fanned accusations of hypocrisy and callousness against the NRA.

"NRA spits on the graves of Newtown massacre victims with release of mobile shoot-'em-up app for iPhone, iPad," ran one headline in the New York Daily News.

The NRA insists the game will be a tool for education and promotion of responsible gun ownership. The game contains no live targets, and all the action takes place at a practice range giving access to educational materials, safety tips and other information.

If you want to check out the app for yourself, head over here.