On Monday the City Council sent a letter to Amazon CEO Jeff Bezos expressing concern over the way security guards hired to protect the company’s Seattle campus and attempting to form a union are being treated by the security subcontractor Security Industry Specialists (SIS).

The council’s letter, which is embedded below, notes that a recent letter from Seattle’s Human Rights Commission to Amazon regarding SIS’s treatment of employees has gone unanswered. “We are deeply concerned about the appearance of retaliation against workers trying to form a union,” the letter reads in part. “We respectfully request that you respond forthwith to this legitimate inquiry.”

Here’s the full letter from the City Council:

Seattle City Council Letter to Amazon Re SIS Workers

The letter was delivered during a press event Wednesday afternoon. According to a press release issued prior to the letter’s deliver, “SIS has been accused by current and past security officers of violating the city’s commitment to the Universal Declaration of Human Rights as well as Amazon’s own Supplier Code of Standards and Responsibilities. SIS security officers face violations of human rights and basic dignity, such as working without bathroom breaks, inability to use paid sick leave, and retaliation for trying to form a union, a fundamental Constitutional freedom.”

“Ensuring that service workers are able to support themselves and their families with living wage jobs is critical to a healthy economy in Seattle,” Councilmember Mike O’Brien said in the press release. “As one of Seattle’s largest employers, we ask that Amazon take full responsibility for ensuring a respect for human rights and national labor law among your direct and subcontracted employees alike.”

Meanwhile, according to the Seattle Times, “Amazon.com shares sank in after-hours trading after the online retail giant posted a second-quarter loss that was larger than Wall Street expected.” Jay Greene of the Times reports that Amazon shares fell by $19.25, settling at $339.36.