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Just as Amazon is finalizing plans for its big Prime Day summer sale next week, the company is facing more labor problems in its Minneapolis-area warehouses.

Workers at its Shakopee, Minnesota, fulfillment center are planning a six-hour strike during Prime Day to push for better working conditions and worker protections, Bloomberg reported Monday.

Amazon warehouse workers in the Twin Cities region have been especially vocal in their efforts to raise labor concerns, with these efforts powered by East African Muslim employees and the local Awood Center, a worker advocacy organization. Employees there have already pushing Amazon's managers to negotiate over firings and worker complaints. In May, three Somali Muslim workers filed charges with the federal Equal Employment Opportunity Commission, claiming Amazon failed to accommodate their religious needs and retaliated against their protests.

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While the strike is unlikely to impact Amazon's operations, it should continue to highlight persistent and ongoing concerns about its treatment of warehouse workers. Unions and advocacy groups have long contended that the company overworks employees and sets up a hostile working environment. Amazon has often responded by pointing to its move last year to raise its wages to $15 an hour, and saying it provides safe working conditions.

"The fact is Amazon offers already what this outside organization is asking for," Amazon said in a statement Monday, highlighting its pay and benefits package, which includes paid education, parental leave and promotional opportunities. "We encourage anyone to compare our pay, benefits, and workplace to other retailers and major employers in the Shakopee community and across the country – and we invite anyone to see for themselves by taking a tour of the facility."

While European Amazon workers have routinely gone on strikes during big sales days, including Prime Day and Black Friday, these types of strikes aren't common in the US, where no Amazon workers are unionized and union protections aren't as strong.

In the past year, Amazon has faced repeated criticism for its warehouse conditions. Last month, for instance, US Representative Alexandria Ocasio-Cortez, a regular critic of the company, said that Amazon pays its workers "starvation wages." Amazon responded by saying that her assertion was "just wrong." Last year, US Senator Bernie Sanders continually attacked Amazon, too, but then congratulated the company for raising its minimum wage to $15.