NORTHAMPTON — Several members of the Massachusetts congressional delegation, including U.S. Rep. Jim McGovern, are demanding an explanation on reports of price disparities found at different Stop & Shop locations in the commonwealth, something the Gazette found also exists in the western part of the state.

In a letter addressed to Frans Muller, the CEO of Stop & Shop’s parent company Ahold Delhaize, the delegation cited an investigation done last year by a Boston youth group, Hyde Square Task Force, that looked at several grocery items at a Stop & Shop location in the Jamaica Plain neighborhood of Boston and compared them to a store location in Dedham, an affluent Boston suburb. The group found that the Boston location charged more for many of the items on the list, with discrepancies frequently reaching 20% or higher.

“These types of price discrepancies place significant burdens on already-struggling consumers,” the letter states. “Stop & Shop’s actions appear to reflect a problem of opportunistic and sometimes-predatory pricing practices by major food and grocery corporations in the United States.”

The letter was signed by McGovern along with fellow U.S. Rep. Ayanna Pressley, and U.S. Sens. Elizabeth Warren and Ed Markey, all of whom are Democrats from Massachusetts. The letter comes as the party’s presidential candidate and current Vice President Kamala Harris has blamed corporate price gouging for the persistent high cost of goods, pledging to crack down on the practice if elected president.

The Gazette also looked at if price discrepancies existed in the western part of the state, using the same products examined by the Hyde Square Task Force and comparing prices in two locations: the Stop & Shop located at 228 King St. in Northampton and another one located at 28 Lincoln St. in Holyoke. The Gazette found price disparities continued to exist between several of the products, but that prices fluctuated between both stores, unlike the discrepancy found between the Jamaica Plain and Dedham locations.

For example, the Gazette found that a box of the frozen Bubba Turkey Burgers cost $9.69 in Northampton and $10.29 in Holyoke, a 6% difference. The same product cost $9.49 in Dedham and $11.49 in Jamaica Plain, according to the youth group study.

But a package of Nathan’s beef skinless hot dogs, another product on the list, cost $5.99 in Holyoke and $6.49 in Northampton, a difference of 8%. The Holyoke store matched the Dedham store price, while the Jamaica Plain store listed the product at $6.99.

The letter notes that Stop & Shop responded to the original study back in February, denying the youth group’s findings and saying the price difference between the locations was less than they had reported.

In addition to price differences, the delegation also warned of grocery store chains’ increasing use of electronic shelving labels, saying it had the potential to be abused and rapidly fluctuate prices based on temporary factors such as the weather or time of day.

“By updating price tags with the simple click of a button, corporations will be able to suddenly raise the consumer costs at times when certain products are in highest demand,” the delegation wrote. “These abuses are possible because a handful of giant food and grocery companies dominate each level of the supply chain.”

The delegation is requesting that Stop & Shop disclose its pricing algorithm together with listing all factors that go into pricing decision, providing updated prices for the products at the Jamaica Plain and Dedham locations, cost of leasing the two spaces and the highest and lowest prices the products used in the study across the chain’s 124 locations across the state. The company has until Oct. 14 to respond to the letter.

Alexander MacDougall can be reached at amacdougall@gazettenet.com.