Sheikh Sabah has played a key role in shaping up the country's foreign policy.
Kuwait City - Sheikh Sabah was admitted to hospital on Saturday for medical tests
The Amir of Kuwait, His Highness Sheikh Sabah Al Ahmad Al Sabah, underwent a "successful" surgery on Sunday, according to official news agency.
The state-run KUNA news agency had described Sheikh Sabah's hospitalisation on Saturday as "medical checks", citing a statement from the country's royal court.
Several hours later, KUNA published a second report saying that 83-year-old Crown Prince Nawaf Al Ahmad Al Sabah had assumed some of Sheikh Sabah's powers temporarily.
However, a copy of the ministerial decree posted by Kuwait's official gazette, Kuwait Al Youm said the crown prince would be empowered for "the duration of a surgical procedure until the health event is over".
Kuwait's Information Ministry did not immediately respond to a request for comment, though minutes later the state-run KUNA news agency reported Sheikh Sabah underwent a "successful" surgery.
"May God bless his highness and grant him a speedy recovery," the KUNA report said, citing a royal court statement.
In August 2019, Kuwait acknowledged the Amir suffered an unspecified medical "setback" that required him to be hospitalised.
In power since 2006, Sheikh Sabah has pushed for diplomacy to solve regional issues and hosted major donor conferences for war-torn nations like Iraq and Syria.