US Defense Secretary Lloyd Austin was released from the hospital on Tuesday, after undergoing treatment under general anesthetic for bladder issues as he suffers from prostate cancer, the Pentagon confirmed.

On Monday, Pentagon spokesman Pat Ryder announced that Austin had transferred his duties to his deputy hours after he was taken to hospital for "an emergent bladder issue."

"He is recovering well and resumed his full functions and duties today at 5:00 pm (2200 GMT)... Secretary Austin will recuperate and perform his duties remotely from home for a period before returning to work at the Pentagon later this week," the Defense chief's office said in a statement on Tuesday.

The White House and Congress have been notified of his return to work, the Pentagon said.

Austin had been scheduled to attend a meeting in Brussels of the Ukraine Defense Contact Group of nations coordinating military assistance, but the Pentagon canceled those plans and announced the meeting would instead be virtual.

The announcement came weeks after it emerged that Austin, 70, had kept previous hospital stays secret and had not immediately informed US President Joe Biden of his cancer diagnosis, sparking criticism as the United States faces crises in the Middle East and Ukraine.

Austin effectively vanished from the public eye for treatment for prostate cancer in December and again in January after suffering complications from the procedure.

He publicly apologized for not revealing the hospitalizations, and the administration has launched investigations into how the chain of command operates when senior officials are incapacitated.

"Frankly, my first instinct was to keep it private. I don't think it's news that -- I'm a pretty private guy -- I never liked burdening others with my problems," he said.

National Security Council spokesman John Kirby was asked by reporters on Monday if Biden had any concerns over Austin's ability to continue in his job, and he replied: "Not at all."