Wal-Mart Stores Inc. has decided to stop selling guns in about a third of its U.S. stores in what it calls a marketing decision based on lack of demand in some places, a company spokeswoman said Friday.

The world’s largest retailer decided last month to remove firearms from about 1,000 stores in favor of stocking other sporting goods, in line with a “Store of the Community” strategy for boosting sales by paying closer attention to local differences in demand.

“This decision is based on diminished customer relevancy and demand in these markets,” said Jolanda Stewart, Wal-Mart spokeswoman.

Hunting and shooting advocates said it was a surprise that Wal-Mart, which has a strong hunting and fishing tradition, would surrender the field in at least some areas to big-box outfitting stores like Bass Pro Shops and Cabela’s.

“For some folks, it will affect them as far as where they get their deer rifle or shotgun,” said Gregg Patterson, spokesman for the hunting and conservation group Ducks Unlimited.

The National Rifle Assn. said it was concerned people in rural areas, where Wal-Mart may be the only purveyor, may no longer have access to guns.

“We’ve been told by Wal-Mart that the decision would be made on a store-by-store basis based on demand. The NRA and our members will be watching closely to make sure they stay true to their word,” NRA chief lobbyist Chris Cox said.

The change could be a boon for mom-and-pop hunting stores that lost business when Wal-Mart moved in, said Steve Wagner, spokesman for the National Shooting Sports Foundation, the trade association for the shooting, hunting and firearms industry.

Wal-Mart’s critics and gun control advocates welcomed the move.

“This a good first step,” said Paul Blank, director of the union-funded group WakeUpWalMart.com, which contends there is a growing public safety concern about violence and crime at Wal-Mart stores.

The Violence Policy Center, a gun control group, said Wal-Mart’s decision reflected what it called a decline in gun ownership. “The marketplace has spoken and the losers are America’s gun industry and the gun lobby,” VPC Executive Director Josh Sugarmann said.

Wal-Mart’s Stewart declined to specify what stores were affected. Wal-Mart, based in Bentonville, Ark., has about 1,200 discount stores and 1,900 supercenters.