Scarborough-based Hannaford Supermarkets saw sales increase $100 million during its third quarter, attributable in part to a prolonged customer boycott of rival Market Basket.

Belgium-based Delhaize Group, the parent company of Hannaford, said in an earnings call late last week that the increased sales were a result of customers choosing to shop at about 30 Hannaford stores whose locations overlap with the Massachusetts-based supermarket chain.

Market Basket stores were embroiled in a six-week employee protest this summer over the firing of CEO Arthur T. Demoulas. Workers encouraged customers to shop elsewhere as a show of support for the ousted leader, who was reinstated in an agreement to buy the family-owned supermarket’s remaining shares for $1.5 billion.

Delhaize Group’s CFO said while overall sales spiked, Hannaford also incurred extra expenses because of the need to hire extra workers, so there was no significant net gain.

But Hannaford spokesman Michael Norton said Monday there could be gains that aren’t yet realized.

As painful as it was to witness the struggles of Market Basket’s employees, Norton said, the crisis created an opportunity for Hannaford to gain some new customers.

“We think we did,” he said. “Or even if we didn’t, we left a really good impression.”

He said after the employee dispute erupted at Market Basket, Hannaford stores in overlapping markets experienced an immediate, significant increase in customer traffic.

Store managers had to respond quickly by ordering more inventory and bringing in additional staff to stock shelves and wait on shoppers, he said.

Norton likened it to the boost in volume Hannaford experiences when customers rush to get their shopping done before a major snowstorm.

“The difference is, we had to sustain it for many weeks,” he said.

Micum McIntire, manager for the Biddeford Market Basket – the only Market Basket store in Maine – said in an earlier interview that once the boycott ended Aug. 27, customers returned to the store and sales returned to normal. The privately held company does not release revenue figures, although analysts speculated that Market Basket lost tens of millions of dollars in sales throughout the boycott.

Delhaize also reported its total U.S. revenue, which includes the Food Lion chain, grew 5.9 percent to $4.66 billion in the company’s third quarter.

J. Craig Anderson can be contacted at 791-6390 or at:

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