Jay Carney said the president was "actively supportive" of a Democratic senator's plan to introduce a bill on the first day of the next Congress.

 

There could also be moves on ammunition（弹药） and gun-sale loopholes, Mr Carney said.

 

In its first statement since Friday, the National Rifle Association said it was "heartbroken" by the attack.

 

The gun lobby group said it was "made up of four million moms and dads, sons and daughters - and we were shocked, saddened and heartbroken by the news of the horrific and senseless murders in Newtown.

 

"The NRA is prepared to offer meaningful contributions to help make sure this never happens again," the statement said, announcing a "major news conference" to be held on Friday.

 

Gun sales, including those of assault rifles, have risen since Friday, a sign that enthusiasts fear that new legislation is coming, the BBC's Paul Adams in Washington reports. 

 

At the same time, share prices of several gun manufacturers have fallen and a private equity firm has sold its stake in the company that makes the assault rifle used at Newtown, after pressure from one of its biggest investors, a California teachers retirement fund. 

 

Gunman Adam Lanza killed 20 children and six adults in last Friday's attack.