MEXICO CITY (Reuters) - The Mexican Federal Police harassed migrants and threatened to raid a migrant shelter in Coahuila over the weekend, according to the head of a state agency and the head of the shelter, the latest in a series of similar reported incidents.

FILE PHOTO: A migrant from Central America rests at the stairs of the "Posada Belen" migrant shelter in Saltillo, Mexico June 15, 2014. REUTERS/Daniel Becerril/File Photo

Hugo Morales, president of the state agency, the Coahuila Commission of Human Rights, said he had confirmed multiple online and witness reports that law enforcement officers took action at the Casa Migrante Saltillo, in the northern Mexican city of Saltillo on Saturday, one day before U.S. Secretary of State Mike Pompeo praised the country’s efforts to quell U.S.-bound migration, under a June deal which averted threatened tariffs by President Donald Trump.

“Unfortunately, now that officials are harassing shelters across the country, migrants no longer feel safe relying on them,” Morales said.

The Federal Police did not immediately respond to requests for comment.

The operation is one in a series of reported incidents in the past month in which federal officers, either members of the Federal Police or of the newly formed National Guard, have approached and threatened to raid similar shelters..

The National Guard also did not immediately respond to a request for comment.

Other confirmed approaches by national officials to enter and search migrant shelters have occurred in Tenosique, Tijuana and Agua Prieta.

Jose Maria Garcia, director of a shelter in Tijuana, said migrants transiting in Mexico are more vulnerable to authorities than they were in the past.

“It is strange, now authorities are even asking people for documents in bus stations when they are thought to look like migrants,” Garcia said.

The United Nations, in response to news of the federal police presence at the Saltillo shelter, in a statement on social media on Saturday called for Mexico to “comply with its Migration law” in light of the “possible immigration verification operation” in the city.

Mexican immigration law prohibits migration verification visits in places where migrants are “housed by civil society organizations, or people carrying out acts of humanitarian assistance or protection.”

Mexican Foreign Minister Marcelo Ebrard, when asked at a news conference on Monday about the entry of federal police in migrant shelters, said: “In principle I do not know of any indication that the Federal Police or other agencies enter civil society shelters under any circumstances, other than at the request of the shelter itself.”

The director of Casa Migrante Saltillo, Alberto Xicotencatl, said federal authorities took action Saturday to monitor the blocks surrounding his shelter, detaining migrants on their way to the safe house. Xicotencatl said four migrants had already reached the building when police caught up and attempted to detain them.

“The police had them by the arms, had them up against the door”, he said.

According to Xicotencatl and a statement posted online by the shelter, coordinator Jose Luis Manzo approached the officers, saying they did not have a legal right to detain migrants on the organization’s property. At that point, Xicotencatl said, officers threatened to enter the building in search of other migrants without Mexican immigration documents before leaving empty-handed.

Morales said the Coahuila Commission of Human Rights had independently confirmed the police visit and has opened an investigation into the Federal Police actions.