In this Aug. 3, 2017, file photo, packages ride on a conveyor system at an Amazon fulfillment center in Baltimore. Amazon's Prime Day starts July 16, 2018, and will be six hours longer than last year's and will launch new products. Credit: Patrick Semansky | AP

Amazon workers, who have long gone on strike in the run-up to the holidays, have found a new occasion to get their employer’s attention: “Prime Day.”

Nearly 1,800 Amazon workers in Spain went on strike Monday during Prime Day, which has quickly grown into the company’s biggest-sales day of the year. Thousands more Amazon employees in Poland and Germany are expected to walk off the job on Tuesday, the second day of the 36-hour sale, for similar reasons. The unions that represent the warehouse workers, Comisiones Obreras and Verdi services union, say they are calling for better working conditions, pay and health benefits.

“The message is clear — while the online giant gets rich, it is saving money on the health of its workers,” Stefanie Nutzenberger, a spokeswoman for Verdi, which represents German workers, said in a statement on its website.

This week’s labor protests underscore a growing challenge for Amazon: It is facing increased scrutiny over its hiring and labor practices at a time when it’s looking to add thousands of new warehouse workers and growing at breakneck speed.

Amazon and its billionaire founder, Jeff Bezos, have a long history of thwarting unionization efforts in the U.S. (Bezos also owns the Washington Post, where last week unionized employees approved a new contract with the company after 14 months of tense negotiations.)

But in Europe, where unionization is more widespread, labor unions have been on the front lines of calling for workers’ rights at the company’s warehouse facilities, where physical demands can be grueling and temperatures can reach extremes. Until now, though, most of their efforts have been centered around the critical holiday season. Last November, for example, hundreds of Amazon workers in Italy and Germany went on strike, saying they were under “high pressure to create more and more in less time.

A spokeswoman for the Seattle-based giant said it was committed to providing workers with “positive working conditions.”

“Amazon is a fair and responsible employer and as such we are committed to dialogue, which is an inseparable part of our culture,” spokeswoman Melanie Etches said in an email.

This week’s strikes have also inspired widespread calls for shopper boycotts on social media platforms such as Twitter.

In the U.S., advocacy groups are planning a series of consumer rallies outside of Amazon-owned Whole Foods Market locations to protest the sale of Nazi, confederate and white nationalist merchandise sold through Amazon’s marketplace of third-party sellers. There have also been widespread calls on social media for shoppers to boycott Amazon during Prime Day, which this year begins Monday afternoon and continues through Tuesday.

“People are demanding change, not just from politicians but also businesses,” the Action Center on Race and the Economy said in a statement promoting Whole Foods protests. “The goal of #PrimeDayofAction is to raise awareness about the harmful practices of the nation’s largest online retailer and to ask: is there anything Amazon won’t do for a dollar?”

“Amazon is a massive behemoth — it will take more than a strike in Spain to rattle its cage,” said Peter Horst, founder of marketing consulting firm CMO Inc. “But at the same time, these strikes create a moment for consumers to pause and say, ‘What’s happening here? I love these low prices but I’m also starting to have sympathy for some of these workers.’”

He and others pointed to Walmart, Amazon’s largest competitor, as a cautionary tale. The company has become the world’s largest retailer, mostly by offering rock-bottom prices, but it has also received widespread criticism for the treatment of its workers, some of whom say they have had to rely on government programs to make ends meet.

It is too soon to tell, protest organizers said, how the workers’ strikes might impact shipments throughout Europe. “It is a priority of Amazon to serve and keep our customers’ delivery promises,” said Etches of Amazon.

Employee walk-outs in Germany are expected to impact six warehouses, while labor organizers in Spain say roughly 96 percent of workers at the company’s San Fernando warehouse outside Madrid are currently on strike. (Amazon disputed that figure and said “the majority” of employees were at work on Monday.)

This year’s Prime Day is expected to bring in $3.4 billion for the company, up from an estimated $2.4 billion a year ago, according to retail research firm Coresight Research. Amazon created the discount event four years ago to mark the company’s 20th anniversary.

A number of other retailers including Target, Macy’s, Kohl’s and eBay are also promoting discounts throughout the week.

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