WASHINGTON (REUTERS) - Vice-President Joe Biden said on Wednesday the White House plans to act quickly to curb gun violence and will explore all avenues - including executive orders that would not require the approval of Congress - to try to prevent incidents like last month's massacre at a Connecticut school.

Kicking off a series of White House meetings on gun violence, Mr Biden said the administration would work with gun-control advocates and gun-rights supporters to build a political consensus on restrictions. But Mr Biden made clear that President Barack Obama is prepared to act on his own if necessary.

"We are not going to get caught up in the notion that unless we can do everything, we're going to do nothing. It's critically important that we act," said Mr Biden, who on Thursday will meet with pro-gun groups including the National Rifle Association (NRA), which claims 4 million members and is the gun lobby's most prominent organisation.

Mr Biden, whose panel was formed after 20 schoolchildren and six adults were killed on Dec 14 by a gunman at an elementary school in Newtown, Connecticut, has been ordered by Mr Obama to come up with policy proposals on guns by the end of January.

The Vice-President said there was a consensus on "three or four or five" steps regarding gun safety, but did not specify what they were.

"There are executive orders, executive action that can be taken. We haven't decided what that is yet," Mr Biden said, adding that Mr Obama is conferring with Attorney General Eric Holder on potential action.

Mr Biden's group is expected to recommend a reinstatement of an assault weapons ban that Congress allowed to expire in 2004.

The Washington Post has reported that Mr Biden's group also will seek broad restrictions that include tracking the sale and movement of weapons via a national database, and stiffer checks on the mental health of prospective gun buyers.

During his daily briefing, White House spokesman Jay Carney declined to discuss any action Mr Obama might take on his own on guns. "Those decisions haven't been made," Mr Carney said.

The Connecticut school shootings galvanised activists on both sides of the gun-control issue. In Washington and across the nation, the slayings inspired new calls for more restrictive gun laws and led gun-rights advocates to mobilise in opposition.

Mr Obama promised to put gun control at the top of his agenda after he begins his second term on Jan 20, but the issue will have to compete with a crush of other priorities including a looming budget confrontation with congressional Republicans.

There have been other pushes for gun control in recent years, but such efforts typically have been sidetracked by the influential gun lobby, which enjoys widespread support among Republicans and significant backing among Democrats as well.

But now, "The President and I are determined to take action," Mr Biden said at Wednesday's meeting with gun violence victims and gun-control advocates.

"This is not an exercise in photo opportunities or just getting to ask you all what your opinions are. We're reaching out to all parties on whatever side of the debate you fall," he said.

Wal-Mart Stores Inc, the largest US gun seller, also will participate in Thursday's White House meetings.

Wal-Mart reversed its initial decision not to send anyone to the Mr Biden gathering to share the company's position.

"We underestimated the expectation to attend the meeting on Thursday in person, so we are sending an appropriate representative to participate," spokesman David Tovar said.

Even without action by Congress, Mr Obama could issue orders to improve background checks on gun buyers, ban certain gun imports and bolster oversight of dealers. Other executive orders could improve information sharing among law enforcement authorities about illegal gun purchases, and maintain data on gun sales for longer periods.

Mr Obama has said he believes most Americans support the reinstatement of a ban on the sale of military-style assault weapons, barring the sale of high-capacity ammunition clips, and a law requiring background checks on buyers before all gun purchases.

It is unclear whether any of those measures will have more support in Congress after the Connecticut massacre than they did after previous mass shootings.

With the federal outcome uncertain, some states are taking action on their own. The Connecticut state legislature convened on Wednesday for the first time since the shootings, and new gun measures will be high on the agenda.

New York Governor Andrew Cuomo will propose a more restrictive law on assault weapons. Governors and state legislatures in Maryland, Virginia, Illinois and elsewhere will consider new gun laws.

A federal appeals court signaled on Wednesday it is prepared to uphold one of the few gun control measures put forward so far by the Obama administration - a regulation designed to detect the sale of semi-automatic rifles to Mexican drug cartels.

Gun retailers and manufacturers, including a trade group based in Newtown, said the rule is burdensome and violates federal law.

The measure requires stores in the four US states bordering Mexico to send a notice to federal law enforcement whenever someone buys two or more or a certain kind of high-calibre, semi-automatic rifle with a detachable magazine.

The court is expected to rule on the case within the next few months. During a hearing on Wednesday, the court's three judges repeatedly questioned whether the rule created too much extra work for gun sellers and manufacturers.