President Barack Obama has extended his support for a ban on assault weapons, as the United States continues to come to terms with the Sandy Hook Elementary School massacre in Newtown, Connecticut.

The American president is "actively supportive" of Democrat Senator Dianne Feinstein's demand for a Congressional bill reinstating the nationwide ban on assault weapons, according to White House press secretary Jay Carney.

"He [Obama] is actively supportive of, for example, Senator [Dianne] Feinstein's stated intent to revive a piece of legislation that would reinstate the assault weapons ban," said Carney during his regular press briefing at Washington.

He said that Obama would specifically support the "legislation that addresses the problem of the so-called 'gun show loophole", which allows individuals 'not engaged in the business' of weapons retail to sell guns without a licence.

Carney added that "there are other elements of gun legislation that he [Obama] could support... high capacity ammunition clips, for example."

Former President Bill Clinton introduced a ban on assault weapons in 1994, but this ban expired 10 years later and has not been reactivated.

Following the gun attack at Sandy Hook, which claimed the lives of 20 children and six adults, Feinstein, who heads the Senate Intelligence Committee, has called for the introduction of fresh legislation.

"It will ban the sale, the transfer, the importation, and the possession. Not retroactively, but prospectively. It will ban the same for big clips, drums or strips of more than 10 bullets. There will be a bill," Feinstein told the NBC.

The Democrat senator insisted that the bill would exclude 900 specific weapons as it is aimed at getting the "weapons of war" off the streets of the American cities.

Meanwhile, the powerful National Rifle Association (NRA) lobby has spoken out for the first time since the attack on 14 December.

The Association said it is "shocked, saddened, and heartbroken" over the attack, adding that "the NRA is prepared to offer meaningful contributions to help make sure this never happens again."

The NRA is also planning to hold a "major news conference" in Washington on 21 December where further details may emerge.

The group lobbies for relaxing the restrictions on gun sales and ownership, and encouraging gun-related sports and activities.

The gun sales across the US appeared to have soared since the attack, evidently in fear of the legislation to restrict gun ownership. Obama also called for a ban on assault weapons during his recent presidential campaign.

Alongside, the funerals for the victims continue to take place in Newtown.