A prominent United States gun rights advocate called for a campaign to overturn state-level weapon control laws, claiming they were "lethal" and "killing people", as thousands of firearms enthusiasts rallied at "Guns Save Lives Day" shows.

The provocative display of defiance by the gun lobby came after America marked the first anniversary of the Sandy Hook massacre and a teenage girl was critically ill in Colorado following the latest school shooting.

Claire Davis, 17, was shot in the head by Karl Pierson, 18, a fellow student at Arapahoe high school who was armed with a legally purchased shotgun, a machete, three Molotov cocktails and ammunition belts.

Pierson, who was hunting a teacher against whom he had a grudge, planned to harm "a large number of individuals" in a commando-style attack, but killed himself just over a minute after he entered the school, investigators said.

The polarising divide about how to tackle the gun violence epidemic was on sharp display as Larry Pratt, the head of Gun Owners of America, clashed with Mark Kelly, a former astronaut and husband of Gabrielle Giffords, the US congresswoman shot in the head during a shooting rampage.

"Every one of our mass murders in our country has occurred in places where guns are prohibited," Pratt told Fox News.

"The legislation that is on the books is lethal, it is killing people. All of these gun-free zones are murder magnets, and we have got to get rid of them.

"It's an illusion to think that somehow we're going to be safer because we can't have a gun in a particular area, because the bad guy is going to have a gun."

Despite the debate set off by the Sandy Hook tragedy, it has been a tough year for supporters of greater gun controls such as Kelly, with even limited federal background check legislation blocked in the Senate.

Campaigners are now focusing their efforts on initiatives to keep firearms away from criminals and the mentally ill at state level.

Even though Kelly noted that of 109 new gun laws passed, two-thirds loosened restrictions, he said that the group he founded with his wife was preparing to spend US$25 million ($30.2 million) in the 2014 mid-term election cycle in an effort to combat the better-financed gun lobby.

"We are going to get members of Congress to think differently about the next election and then we will see some real change," he said.

President Barack Obama used his weekly presidential address to repeat his call for action. "We have to do more to keep dangerous people from getting their hands on a gun so easily. We have to do more to heal troubled minds," he said. "Beneath the sadness, we also felt a sense of resolve - that these tragedies must end, and that to end them, we must change."

But gun rights advocates oppose even new background checks on firearms sales for mental health and criminal records. Organisers of yesterday's "Guns Save Lives Day" accused supporters of tougher restrictions of "shamelessly exploiting" the anniversary of the tragedy at Sandy Hook school in Newtown.

They had originally planned to hold the event on Sunday, the anniversary, but postponed it a day after criticism. "No one at Newtown should have been a victim," said Alan Gottlieb, an officer with the Second Amendment Foundation that helped stage the day. He argued that all Americans, even in schools, should be allowed to defend themselves.

- Daily Telegraph UK