The statement said the 84-year-old king is being tested at the King Faisal Specialist Hospital. The brief statement did not provide further details.
King Salman has been in power since January 2015. He is considered the last Saudi monarch of his generation of brothers who have held power since the death of their father and founder of Saudi Arabia, King Abdulaziz.
King Salman has empowered his 34-year-old son, Crown Prince Mohammed bin Salman, as his successor.