Acting U.S. border chief John Sanders resigns

June 25 (UPI) -- Acting U.S. Customs and Border Protection chief John Sanders, under pressure to address increasing numbers of migrants crossing the border and the condition of detention facilities, told employees Tuesday he will resign.

Sanders didn't cite a reason for his departure, but it follows the relocation of more than 200 detained children after reports of unsanitary conditions and inadequate food. U.S. officials returned about 100 children to an overcrowded Border Patrol facility in Clint, Texas, over the weekend and Monday because of a lack of bed space at shelters.

CNN reported Sanders informed his employees in an email of his resignation effective July 5.

"Although I will leave it to you to determine whether I was successful, I can unequivocally say that helping support the amazing men and women of his CBP has been the most fulfilling and satisfying opportunity of my career," Sanders said in a statement.

President Donald Trump said he didn't ask Sanders to resign, but he was aware of his departure ahead of time. The president told reporters he's "very concerned" about the conditions at migrant detention facilities.

Sanders took over as acting CBP commissioner after Kevin McAleenan was promoted to acting Homeland Security secretary in the spring.

Rep. Veronica Escobar, R-Texas, said she'd sent a letter to Sanders about conditions at the Clint facility.

"Children do not belong in detention and @realDonaldTrump's failed policies are only harming children and promoting needless and cruel family separation," she tweeted.

Migrant living conditions at facilities on the U.S.-Mexico border have been criticized for months. At a processing center in McAllen, Texas, migrant children are stuck in overcrowded spaces, forced to sleep outside and drink contaminated water.

Acting Immigration and Customs Enforcement Director Mark Morgan was given a green light this month to carry out mass deportations after Trump postponed raids in multiple U.S. cities.