When Mayor Bill de Blasio defends New York’s “sanctuary city” policies, he often cites a public safety rationale. Immigrants must feel free to report crimes to police without fear of deportation, he says.

“If you really want safe streets, police have to be able to have an open and unfettered relationship with immigrant communities,” he told radio listeners last year.

But a complaint filed with the city’s Commission on Human Rights and joined on Monday by the immigrant advocacy group Make the Road New York details a challenge to the mayor’s argument. Three New Yorkers charge the police department with discrimination based on national origin because of the difficulties they faced attempting to speak with police in Spanish. The advocacy group says this is a widespread problem, an accusation the department has refuted.

Iris Vega, 27, was at work at the Gato Verde sports bar in Jackson Heights when her boss ordered her to have a beer and told her that he wanted to have sex with her, according to the complaint filed last year. After Vega refused, the manager physically attacked her, the complaint alleges, and a customer stopped him before he could smash a bottle raised over Vega’s head. She called 911.

But none of the officers who showed up on the scene spoke Spanish, according to the complaint, and no report was filed. She repeatedly visited two local precincts but could not get help in Spanish or the order of protection she sought until Make the Road became involved, the complaint alleges.

“I just wish they had taken my case seriously, that they would have provided me with someone to help communicate in Spanish, not given me the run-around,” Vega told POLITICO in Spanish. “They sent me from place to place without ever giving me anything in writing.”

Another complainant, a woman working in a chicken slaughterhouse in Flushing, was arrested after a coworker who she says was sexually harassing her told police that she had threatened him. Without interpretation, she could not explain the situation to the officers. The third complainant, a gay man living in Elmhurst, was attacked by his landlady’s homophobic brother, he alleges, but when he tried to tell his side of the story at the local stationhouse, no interpretation was available.

The organization argues that it should not have to fill a translation gap at police precincts.

“Our organizers, our attorneys have gone to the precincts with our members and clients to make sure that they provide meaningful interpretation — which is something that they should have done anyway,” said Make the Road attorney Cristobal Gutierrez.

Under local law, places of “public accommodation” — doctor’s offices, schools, banks and government agencies, for example — cannot deny services based on factors such as national origin, race or gender.

Make the Road argues that police services count as public accommodations. NYPD disagrees with the group’s argument. The police department did not respond to a request for comment for this article, but defended itself in an October rebuttal of the complaint.

The department also rejected the idea that the allegedly insufficient translation services would be a form of discrimination based on national origin. It took the position that the three complainants were not denied services, and that the cases do not amount to a “policy and practice.” The department contends that it has an effective language access plan, as mandated by a Bloomberg-era executive order.

Vega said she will be more hesitant if she needs police assistance again.

“Honestly I’ve lost faith in them, I don’t feel that I can trust them,” she said. “They didn’t have any respect for me or people like me, Hispanic people.”