Sultan Qaboos bin Said — the Middle East's longest-ruling monarch — underwent medical treatment in Belgium last month after his health deteriorated. Qaboos was a proponent of peace between the US and Iran.
The Sultan of Oman, Qaboos bin Said, has died at the age of 79, according to Oman state TV and the state news agency early on Saturday.
State TV shortly afterward named Oman's culture minister, Haitham bin Tariq Al Said, the Arab country's new ruling sultan.
There were concerns about Qaboos's health after he underwent medical treatment in Belgium last month. Some reports claim he had been suffering from cancer.
Qaboos had ruled the Gulf Arab state for 50 years. In 1970, he took over the country in a bloodless coup with the help of Oman's former colonial power, Britain.
The sultan was known for his diplomatic skills, as he tried to mediate between the US and Iran.
Oman state TV on Saturday said Haitham, a cousin of the late sultan, was named the new ruling sultan.
Qaboos had no children to succeed him, forcing the ruling family to choose a successor within three days of the throne becoming vacant. If the family council had failed to agree, a council of military and security officials, Supreme Court chiefs and heads of the two assemblies would have nominated the person whose name has been secretly written by the sultan in a sealed letter.
Shortly before Haitham was named successor, Oman state TV said authorities had opened such a letter by Qaboos naming his successor — but did not provide further details.
The sultan of Oman is the most powerful figure in the country, holding the positions of prime minister, supreme commander of the armed forces, minister of defense, minister of finance and minister of foreign affairs.
The authorities have announced a three-day mourning period to pay respect to Qaboos, state media said.