The commander of the US prison camp at Guantánamo Bay, Cuba was abruptly fired for unknown reasons over the weekend.

Navy R Adm John Ring was relieved of his duties on Saturday. A statement from US Southern Command said the change in leadership was “due to a loss of confidence in his ability to command”, and would “not interrupt the safe, humane, legal care and custody provided to the detainee population” at Guantánamo.

Earlier this month, Ring had expressed frustration at the difficulties of dealing with an ageing population of detainees, swept up the “war on terror” and held on the base for up to 17 years, without proper resources.

“I’m sort of caught between a rock and a hard place,” Ring told reporters. “The Geneva conventions’ article three, that says that I have to give the detainees equivalent medical care that I would give to a trooper. But if a trooper got sick, I’d send him home to the United States.

“And so I’m stuck. Whatever I’m going to do, I have to do here.”

Officials said the decision to relieve Ring of his command was not connected to the interviews he gave on detainees’ health issues, but was the result of a month-long investigation that had been submitted to the head of Southern Command, Adm Craig Faller, in mid-April.

Ring was summoned to Faller’s headquarters in Florida on Saturday and told of the decision there. Officials would not confirm his current whereabouts, but said he would be temporarily assigned duties elsewhere in Southern Command’s area of operations, which includes Latin America and the Caribbean.

“The vast majority of commanders complete their assigned tours with distinction,” a Southern Command statement said. “When they fall short, we hold our leaders accountable, which reflects the importance we place on the public’s trust and confidence in our military leaders.”

Ring’s deputy, army Brig Gen John Hussey, has been made acting commander of the joint taskforce running the Guantánamo camp on the southern coast of Cuba.

The camp, established at the beginning of 2002, currently houses 40 prisoners, most of whom have never been charged. At its peak, in 2003, it held more than 700. Barack Obama tried to close it, but failed to overcome resistance from Congress and the Pentagon. Donald Trump has vowed to keep it opened and raised the prospect he could send more inmates there.