Kuwait says its 90-year-old ruling emir has been admitted to a U.S. hospital after an earlier health scare and will cancel an upcoming visit Thursday with President Donald Trump.

The state-run KUNA news agency reported late Sunday that Sheikh Sabah Ahmad Al Sabah was undergoing unspecified medical tests, without elaborating.

The news agency quoted the minister of the emir's diwan council as praying "to Allah the Almighty to bestow His Highness the emir with good health."

On Aug. 18, Kuwait acknowledged the emir suffered an unspecified medical "setback."

That came after visiting Iranian Foreign Minister Mohammad Javad Zarif wrote on Twitter that he was "praying for emir's speedy recovery," without elaborating.

Sheikh Sabah has ruled Kuwait since January 2006. He's pushed for diplomacy to solve regional issues