Oman’s Sultan Qaboos bin Said has died at the age of 79, the state media reported on Friday evening.
Sultan Qaboos ruled has Oman since 1970 after overthrowing his father in a bloodless coup.
The news agency said a three-day mourning period will be observed and the country’s flags will be flown at half-mast for the next forty days.
The Sultan, the longest-ruling Arab monarch, has been had been suffering from what is believed to be colon cancer.
Sultan Qaboos recently returned to the country from Belgium and Germany where he was undergoing specialized treatment.
Sultan Qaboos will be remembered for transforming the country, with a population of 4.5 million people, into a modern state.