NEW YORK — Three major U.S. airlines have asked the federal government to refrain from using their flights to transport migrant children who have been separated from their families as part of the Trump administration’s policy on illegal immigration.American Airlines, United and Frontier issued statements on the matter on Wednesday, before news emerged that President Donald Trump planned to issue an order to end the immediate separation of families detained at the U.S.-Mexico border for entering the country illegally.“The family separation process that has been widely publicized is not at all aligned with the values of American Airlines - we bring families together, not apart,” American Airlines said.United Chief Executive Oscar Munoz said in a statement the policy that has led to family separations is “in deep conflict with our company’s values.”“We have contacted federal officials to inform them that they should not transport immigrant children on United aircraft who have been separated from their parents,” Munoz said.Frontier said in a tweet it “prides itself on being a family airline and we will not knowingly allow our flights to be used to transport migrant children away from their families.”The Department of Homeland Security criticized the airlines’ decisions, saying in a statement it was “unfortunate” that carriers “no longer want to partner with the brave men and women of DHS to protect the traveling public.”Delta Air Lines and Southwest Airlines did not respond to requests for comment on their policies regarding transporting separated migrant children.Videos of youngsters in cages and an audiotape of wailing children have sparked anger in the United States from groups ranging from clergy to influential business leaders, as well as condemnation from abroad, including Pope Francis.(Reporting by Alana Wise; Editing by Phil Berlowitz and Frances Kerry)