A protester holds a sign during a rally against President Trump's immigrant family separation policies in Philadelphia on June 30. (Dominick Reuter/AFP/Getty Images)

Four members of a Homeland Security advisory council have resigned in protest over the Trump administration's immigration policies, citing the “morally repugnant” practice of separating immigrant families at the border.

Richard Danzig, former secretary of the Navy in the Clinton administration, and Elizabeth Holtzman, a former Democratic congresswoman, were among the group that announced their resignation Monday in a letter to Homeland Security Secretary Kirstjen Nielsen.

The group noted that the Department of Homeland Security did not consult its advisory council before implementing the policy, which separated more than 2,500 children until President Trump reversed his endorsement of the practice amid an international outcry and signed an order instructing the agency to stop doing so.

“Were we consulted, we would have observed that routinely taking children from migrant parents was morally repugnant, counter-productive and ill-considered,” the group wrote. “We cannot tolerate association with the immigration policies of this administration, nor the illusion that we are consulted on these matters.”

Two former Obama administration officials — David Martin, a former DHS deputy general counsel, and Matthew Olsen, who served as director of the National Counterterrorism Center — also signed the letter.

Bill Bratton, a former New York City police commissioner who is vice chairman of the advisory council, thanked the group for their service in an email reply, but he did not respond directly to the criticism.

“Each of you was appointed owing to lifelong dedication to the nation and her people, and, indeed, I can appreciate that each of you sees this resignation as part of that dedication,” Bratton wrote.

Tyler Houlton, a DHS spokesman, said it was "disappointing, but not surprising, that appointees from the previous Administration would resign."

He added: "It is unfortunate that instead of first bringing their concerns directly to the Secretary in the spirit of an Advisory Committee member, they chose to simply resign four weeks after the Administration ended the practice of concern."

Advisory council members are appointed by the homeland security secretary to two-year terms. After the resignations, there are 24 members, according to the DHS website. The council meets infrequently, usually no more than twice a year, and includes subcommittees to conduct research and recommendations on DHS policies.

The Trump administration began routinely separating immigrant families who did not have authorization to enter the United States under a new policy that aimed to criminally prosecute all adults who entered the country illegally. To do so, DHS officials said, the administration was required to take away minor children because U.S. law prevents them from being held in adult jails. The agency is struggling to reunite the children with their parents, despite a court order to do so.

In separate letters also sent to Nielsen, Martin and Holtzman also cited objections more broadly to the administration's immigration policies, including an entry ban on immigrants from several majority-Muslim countries, the pursuit of billions of dollars for a border wall and Trump's attempts to end a deferred action program for younger immigrants who have lived in the country illegally since they were children.

“These actions have fueled polarization, alienated state and local governments, and moved us much further from a sustainable, effective, and strategically sensible immigration enforcement program,” Martin wrote.

Holtzman, who like Martin was appointed by former DHS secretary Jeh Johnson during the Obama administration, wrote to Nielsen that under Trump, “DHS has been transformed into an agency that is making war on immigrants and refugees.”

In an interview, Holtzman said she did not believe the resignations would have an impact on Trump's decision-making on immigration. But she added, “I do think it's important for the American people to see that not everybody connected with the government is a brute, is a lawbreaker and that actually some of us do have a measure of conscience.”