He has traveled abroad for medical reasons at least twice since 2014.
The court statement said the latest checks should take “a limited period of time” but gave no details on his condition.
Qaboos has no children and has not publicly appointed a successor, but he secretly recorded his choice in a sealed envelope addressed to the royal family council.
The sultanate’s Basic Law says the royal family should choose a new sultan within three days of the position falling vacant. Should it fail to reach an agreement, the nation’s defense council, the head of the Supreme Court and the heads of the two chambers of the consultative council would then enforce Qaboos’s choice and enthrone the person he designated in the envelope.
Reporting by Maher Chmaytelli; Editing by Catherine Evans and Andrew CawthorneOur Standards:The Thomson Reuters Trust Principles.