PORTLAND — Hannaford Supermarkets urged customers Saturday to return all ground beef for a refund, if they’re worried about its being part of the recall of contaminated meat.

Stores have been receiving dozens of calls from people who, for instance, removed the original packaging and label to freeze the beef, said Michael Norton, a company spokesman. The customers want to know if they can take it back, even if it no longer has a label.

“If you have beef from us and you have a question, bring it to us and we’ll give a full refund,” Norton said.

Norton’s comments came two days after Hannaford issued a recall of all ground beef with sell-by dates of Dec. 17 or earlier.

An outbreak of a rare strain of salmonella has sickened at least 14 people in the U.S. Ten of them, including four from Maine, said they bought ground beef at Hannaford stores, according to state epidemiologist Dr. Stephen Sears. Seven of the 10, including two from Maine, were hospitalized.

Federal investigators are working to determine the source of the contamination. A phone call and email to the U.S. Department of Agriculture Saturday weren’t immediately returned. Norton said the supermarket chain is awaiting further word from the agency.

“We stand ready to respond,” he said.

Shoppers interviewed Saturday at the Hannaford Supermarket on Back Cove in Portland seemed either unaware or unconcerned about Thursday’s beef recall.

Of the five shoppers interviewed, two said they weren’t aware of the problem. One couple said they are vegetarians. Another said they buy only fresh-ground beef at Pat’s Meat Market in Portland.

Erik Hellstedt of Portland said he buys meat at Hannaford, but didn’t have any of the recalled product.

Hellstedt also said the company acted very responsibly. He scrolled through his smartphone to show an email alert on the recall that he received Friday morning.

“I’m not concerned,” he said. “This is something that happens all the time.”

Hannaford, which is based in Scarborough and has stores in five states, is the only grocery chain to issue a recall in response to the salmonella outbreak.

The Hannaford stores that have been linked to illnesses are in Maine, New York, New Hampshire and Vermont, according to the USDA.

Common symptoms of salmonella infection include diarrhea, abdominal cramps and fever within 12 to 72 hours of eating contaminated food, according to the USDA. Other symptoms are chills, headache, nausea and vomiting. They can last for as long as a week.

Salmonella infection can be life-threatening, especially for people with weakened immune systems, including infants, the elderly and people who have HIV or are undergoing chemotherapy.

The USDA urges people to eat ground beef only if it’s cooked to a temperature of 160 degrees, confirmed with a food thermometer.