The most powerful gun lobby in the United States stood firm Monday against any additional restraints on firearms and ammunition sales -- despite a national outcry in the wake of the Sandy Hook school massacre.

Wayne LaPierre, the executive vice president of the National Rifle Association (NRA), said Sunday that planned legislation to outlaw military-style assault weapons and large-capacity magazines was "phony" and would not work.

He repeated the NRA's call to place an armed guard in every school and argued that prosecuting criminals and fixing the mental health system, rather than gun control, were the solutions to America's mass shooting epidemic.

On December 14, a disturbed local man, 20-year-old Adam Lanza, killed his mother in their Newtown, Connecticut home before embarking on a horrific shooting spree at a local elementary school.

He blasted his way into Sandy Hook Elementary School and shot dead 20 six- and seven-year old children and six adults with a military-style assault rifle before taking his own life with a handgun as police closed in.

The bloodshed, the latest in a string of mass shootings in the United States, has reopened a national debate on the country's gun laws, which are far more lax than in most other developed nations.

President Barack Obama said he would support a new bill to ban assault rifles and put Vice President Joe Biden in charge of a panel looking at a wide range of other measures, from school security to mental health.

Democratic Senator Diane Feinstein has pledged to table a bill on January 3 that would ban at least 100 military-style semi-automatic assault weapons, and would curb the transfer, importation and the possession of such arms.

"I think that is a phony piece of legislation, and I do not believe it will pass for this reason," LaPierre told NBC's "Meet the Press." "It is all built on lies that have been found out."

The NRA points to the fact that the 1999 shooting at Columbine High School, when 12 kids and a teacher were gunned down by two senior students, occurred despite similar legislation being in force at the time.

"I don't think it will (work). I keep saying it, and you just won't accept it: it's not going to work, it hasn't worked. (Senator) Dianne Feinstein had her ban and Columbine occurred," LaPierre said.

The 1994 ban, which expired in 2004, prohibited the new manufacture and sale of 19 specific gun models and close copies of those models. It also drew a list of components - such as a detachable magazine or flash suppressor - that could -- from a legal standpoint -- upgrade a firearm to an assault weapon. Firearms with two or more such components were banned.

However, America has suffered an explosion of gun violence over the last three decades including 62 mass shooting incidents since 1982. The vast majority of weapons used have been semi-automatic handguns and rifles obtained legally by the killers.

There were an estimated 310 million non-military firearms in the United States in 2009, roughly one per citizen, and people in America are 20 times more likely to be killed by a gun than someone in another developed country.

The NRA has been in the crosshairs since the Sandy Hook massacre and took the unusual step on Friday of holding a press conference and speaking out on the tragedy.

Rather than come out in support of limited gun control measures, the lobby -- which retains a powerful influence over politicians, especially from rural districts where gun owners are the norm -- demanded that armed police be deployed to every school in the country.

"The only thing that stops a bad guy with a gun is a good guy with a gun," LaPierre told Friday's media event, which was interrupted by hecklers, one holding a banner that read: "N.R.A. Killing Our Kids."

LaPierre reaffirmed the group's position on Sunday and launched a fierce defense of gun owners' rights, which he portrayed as being imperiled by rich folk in cities, elite politicians and a hysterical media.

"The average guy in the country values his freedom, doesn't believe the fact that he can own a gun is part of the problem and doesn't like the media and all these high-profile politicians blaming him," he said.

"If it's crazy to call for putting police and armed security in our schools, then call me crazy," he added. "If I'm a mom or a dad and I'm dropping my child off at school, I feel a whole lot safer."