American Airlines and United Airlines have asked the federal government to refrain from using their flights to transport migrant children who have been separated from their families.

"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 in a statement on Wednesday.

United Chief Executive Oscar Munoz in a statement called the Trump administration's zero tolerance illegal immigration policy that has led to family separations "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.