Former US congresswoman Gabrielle Giffords (left) delivers her opening remarks while seated next to her husband, former US Navy Captain Mark Kelly, during a hearing held by the Senate Judiciary committee about guns and violence on Capitol Hill in Washington.

Washington - Former congresswoman Gabby Giffords, grievously wounded in a 2011 mass shooting, made an emotional plea on Wednesday for Congress to take action to curb US gun violence, but a National Rifle Association executive said new gun laws “have failed in the past and they'll fail again”.

Speaking haltingly, Giffords urged lawmakers to “be courageous” as she opened testimony at the first congressional hearing on gun violence since the December 14 massacre in which a gunman shot dead 20 children and six adults at an elementary school in Newtown, Connecticut.

Responding to outrage across the country following that incident, President Barack Obama and other Democrats have asked Congress to pass the largest package of gun restrictions in decades.

“We must do something. It will be hard, but the time is now,” Giffords, who survived a head wound in an assassination attempt in Tucson, Arizona, told the Senate Judiciary Committee. Six people were killed and 13 wounded in the incident.

“You must act. Be bold, be courageous. Americans are counting on you,” said Giffords, who was accompanied by her husband, former astronaut Mark Kelly.

Obama's proposals to curb gun violence include reinstating the US ban on military-style assault weapons, limiting the capacity of ammunition magazines, and more extensive background checks of prospective gun buyers, largely to verify whether they have a history of crime or mental illness.

Witnesses and lawmakers at the hearing agreed on the constitutional right to own guns but clashed over the proposal for universal background checks for all gun buyers, which is seen as the most likely proposal to gain bipartisan support in a sharply divided Congress.

Wayne LaPierre, executive vice-president and CEO of the powerful gun rights lobbying group the National Rifle Association, dismissed Obama's call for closing loopholes in the background check law.

“Let's be honest, background checks will never be universal because criminals will never submit to them,” LaPierre said.

Kelly said tightening background checks for all gun buyers would be one of the most important ways to prevent guns from falling into the hands of criminals or the mentally ill.

“I mean, I can't think of something that would make our country safer than doing just that,” Kelly testified.

Obama's gun restrictions face a difficult challenge getting through the Democratic-led Senate and Republican-led House of Representatives, where many Republicans and some pro-gun Democrats have long opposed stronger gun-control laws.

LaPierre said the proposals would not reduce gun violence and called for more active prosecution of current laws and improved protection for schools, including armed guards.

“Law-abiding gun owners will not accept blame for the acts of violent or deranged criminals,” LaPierre said. “Nor do we believe the government should dictate what we can lawfully own and use to protect our families.”

“We need to be honest about what works and what does not work. Proposals that would only serve to burden the law-abiding have failed in the past and they'll fail again in the future,” LaPierre added.

Senator Richard Durbin, an Illinois Democrat, sharply challenged LaPierre, saying the city of Chicago in his home state is “awash in guns”.

“We have guns everywhere, and some believe the solution to this is more guns,” he said. “I disagree.”

LaPierre and some Republicans on the panel said there has been a decline in prosecution of gun laws since Obama took office in 2009. “It's a disgrace,” he said.

The most likely common ground in the renewed gun-control debate has been on the proposal for better background checks of gun buyers, rather than Obama's plan to ban the sale of rapid-firing assault weapons like the one used in the Connecticut shootings.

Federally licensed firearms dealers are required to run background checks for criminal records on gun buyers. But the government estimates that 40 percent of purchasers avoid screening by obtaining their guns from private sellers, including those at gun shows.

In a feisty exchange with Judiciary Committee Chairman Patrick Leahy, a Vermont Democrat, LaPierre said the NRA opposed closing the loopholes on background checks for all gun buyers.

“I do not believe, the way the law is working now unfortunately, that it does any good to extend the law,” LaPierre said.

Kelly, who along with Giffords recently founded Americans for Responsible Solutions, a group intended to combat gun violence, said the couple was in favour of gun ownership but against gun violence.

“And we believe that in this debate, Congress should look not towards special interests and ideology - which push us apart - but towards compromise, which brings us together,” Kelly told the senators.

Leahy made clear whatever measures would be considered to rein in gun violence, there would be no move to erode the fundamental right of Americans to own a gun, which is protected under the Second Amendment of the US Constitution.

“Americans have the right to have guns in their home to protect their family,” he said.

Republican Senator Jeff Sessions of Alabama, a former federal prosecutor, agreed with the NRA that the government needs to better enforce existing gun laws.

“You have to prosecute,” Sessions said. - Reuters