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.
The Federal Aviation Administration (FAA) halted traffic on Monday at busy US East Coast airports, snarling more than 1,000 flights after a telecom circuit failed and a backup fibre cable was accidentally cut.
MS NOW, CNN and Politico said on Monday they were suing the Trump Administration to protect their First Amendment rights after President Donald Trump's announcement that he would ban the news outlets from the White House's building grounds.
Pakistan's government said on Monday that it launched airstrikes in the Afghanistan-Pakistan border region, killing at least 28 militants, with one security official saying two Afghan provinces were targeted.
Flights at several British airports were delayed on Monday due to an air traffic control failure, Britain's NATS air traffic control provider said, less than two weeks after a separate issue halted flights across the country.
A fire that broke out at a textile factory in the Chinese city of Foshan in southern Guangdong province on Sunday killed eight people and injured one, state media said on Monday.