King Salman will undergo a treatment programme at Al Salam Palace in Jeddah for a lung inflammation, the state news agency said on Sunday, hours after he underwent medical tests.
Citing the royal court, the state news agency said the 88-year-old king would be treated with antibiotics until the inflammation subsides.
Due to King Salman's health issue, Crown Prince Mohammed bin Salman postponed a visit to Japan that had been scheduled to begin on Monday, Japan's Chief Cabinet Secretary Yoshimasa Hayashi said.
Earlier on Sunday, King Salman underwent medical tests at the royal clinics at Al Salam Palace due to "high temperature and joint pain", the state news agency said.
The king was last admitted to hospital in April for a routine checkup, state TV reported then.
King Salman, the custodian of Islam's holiest sites, became ruler of the world's top oil exporter in 2015 after spending more than 2-1/2 years as the crown prince and deputy premier.
Hundreds of thousands of people in Australia's Queensland state were without power on Sunday after Alfred, a downgraded tropical cyclone, brought damaging winds and heavy rains, sparking flood warnings.
An Israeli airstrike killed two Palestinians in Rafah in the southern Gaza Strip on Saturday, medical sources said, as mediators pushed ahead with talks to extend a shaky 42-day ceasefire agreed in January between Israel and Hamas.
Toronto Police said early on Saturday they were searching for three male suspects in a shooting that injured at least 12 people at a pub in the Canadian city.
Ex-tropical cyclone Alfred lingered off the south-east Australian coast on Saturday and forecasters said Brisbane is likely to miss the worst of the storm, a relief for millions of residents in the region who have been staying indoors.
South Korean President Yoon Suk Yeol walked out of a detention centre in Seoul on Saturday after prosecutors decided not to appeal a court decision to cancel the impeached leader's arrest warrant on insurrection charges.