Donald Trump’s former White House chief of staff has joined the board of directors for Caliburn International, which operates the nation’s largest detention centre for unaccompanied migrant children.

John Kelly reportedly joined the company’s board of directors at some point after leaving the White House at the end of 2018, though it was not immediately clear when he started at the firm.

Before joining the White House administration, he previously served on the board of advisers at DC Capital Partners, which now owns Caliburn International.

Caliburn — which owns Comprehensive Health Services, the company overseeing four children’s detention centres across Texas, including Homestead — confirmed Mr Kelly had joined the board after protesters and media outlets outside one of the centres spotted him touring the grounds back in April.

“With four decades of military and humanitarian leadership, in-depth understanding of international affairs and knowledge of current economic drivers around the world, General Kelly is a strong strategic addition to our team,” Caliburn’s CEO James Van Dusen said in a statement.

Trump shuts down US government over Mexico border wall – in pictures Show all 15 1 /15 Trump shuts down US government over Mexico border wall – in pictures Trump shuts down US government over Mexico border wall – in pictures Federal workers and contractors rally against the partial federal government shutdown Getty Images Trump shuts down US government over Mexico border wall – in pictures The US Capitol on the first morning of a partial government shutdown in Washington EPA Trump shuts down US government over Mexico border wall – in pictures Federal workers and contractors rally against the partial federal government shutdown Getty Trump shuts down US government over Mexico border wall – in pictures President Trump speaks with children who called the North American Aerospace Defense Command Santa tracker in the State Dining Room of the White House. He earlier in the day, tweeted that he was 'all alone in the White House' waiting for Democrats to make a deal on border security EPA Trump shuts down US government over Mexico border wall – in pictures Furloughed federal workers pick up free food at a pop-up store of Kraft Heinz Getty Images Trump shuts down US government over Mexico border wall – in pictures Hundreds of federal workers and contractors rally against the partial federal government shutdown Getty Trump shuts down US government over Mexico border wall – in pictures A pedestrian walk past the U.S. Capitol ahead of a possible partial government shut down in Washington, U.S., December 20, 2018. REUTERS/Joshua Roberts JOSHUA ROBERTS Reuters Trump shuts down US government over Mexico border wall – in pictures From left, House Majority Leader Steny Hoyer, Senate Minority Leader Chuck Schumer, Sen. Dick Durbin and Speaker of the House Nancy Pelosi walk to speak to reporters after meeting with President Donald Trump about border security in the Situation Room of the White House. Trump declared he could keep parts of the government shut down for "months or even years" as he and Democratic leaders failed in a second closed-door meeting to resolve his demand for billions of dollars for a border wall with Mexico Evan Vucci AP Trump shuts down US government over Mexico border wall – in pictures Federal workers and contractors rally against the partial federal government shutdown Getty Images Trump shuts down US government over Mexico border wall – in pictures A sign alerts visitors to the closure of the National Archives on the fifth day of a partial government shutdown EPA Trump shuts down US government over Mexico border wall – in pictures Hundreds of federal workers and contractors rally against the partial federal government shutdown Getty Images Trump shuts down US government over Mexico border wall – in pictures Visitors read signs announcing the closure of the White House Visitor Center EPA Trump shuts down US government over Mexico border wall – in pictures President Donald Trump speaks during a round-table discussion on border security and safe communities with State, local, and community leaders in the Cabinet Room of the White House Getty Images Trump shuts down US government over Mexico border wall – in pictures A sign alerts visitors to the closure of the White House Visitor Center on the first day of a partial government shutdown EPA Trump shuts down US government over Mexico border wall – in pictures Furloughed federal workers show their IDs for entering a pop-up store of Kraft Heinz Getty Images

“Our board remains acutely focused on advising on the safety and welfare of unaccompanied minors who have been entrusted to our care and custody by the Department of Health and Human Services to address a very urgent need in caring for and helping to find appropriate sponsors for these unaccompanied minors,” the CEO’s statement added.

As chief of staff at the White House, Mr Kelly was criticised for his involvement in the administration’s implementation of its zero tolerance policy along the US-Mexico border.

The policy began the systematic separation of families seeking asylum before widespread backlash and nationwide demonstrations demanding better treatment of migrants arriving at the southern border forced the president to walk it back in an executive order.

Critics immediately spoke out against Mr Kelly’s new position, including the migrants’ rights group Families Belong Together.

Support free-thinking journalism and attend Independent events

“John Kelly and the family separation policy he enabled will go down in the history books as a stain on our nation’s moral character,” Jess Morales, chair of the organisation, said in a statement sent to The Independent.