His latest health scare came weeks after it emerged that he kept recent hospital stays secret and had not informed President Joe Biden of his cancer diagnosis, sparking widespread criticism.

Austin, 70, was admitted on Sunday to a critical care ward due to bladder issues after officially transferring duties to his deputy.

He "underwent non-surgical procedures under general anesthesia," his doctors at the Walter Reed National Military Medical Center outside Washington said in a statement.

"A prolonged hospital stay is not anticipated. We anticipate the Secretary will be able to resume his normal duties tomorrow."

The doctors added his cancer prognosis remained excellent.

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

He publicly apologized after coming under heavy political fire for not revealing his hospitalizations.

Austin's health troubles come at a time when the United States faces a spiraling crisis in the Middle East.

The top US defense official is also a key figure in attempts by the Biden administration to maintain support for Ukraine's fight against Russia's invasion, as Republican lawmakers refuse to authorize new funding for military aid to Kyiv.

Some Republicans previously called for Austin to be sacked but Biden has said he remains confident in his defense secretary.

Austin has gained a reputation as an apolitical official who eschews the spotlight, which he said played into his decision to keep his cancer diagnosis secret at first.