Muscat: Sultan Qaboos, the longest-reigning leader of the modern Arab world, has died at the age of 79, the royal court said on Saturday.
"With great sorrow and deep sadness... the royal court mourns His Majesty Sultan Qaboos bin Said, who passed away on Friday," the court said in a statement.
Three days of official mourning have been declared, with flags flown at half-mast for 40 days for the Western-backed Qaboos, 79, who had ruled since taking over in a bloodless coup in 1970 with the help of former colonial power Britain.
State news agency ONA did not give a cause of death, but Qaboos had been unwell for years and spent a week in Belgium undergoing medical treatment in early December.
He left no apparent heir. He was unmarried and had no children or brothers. His cousin Haitham bin Tariq al-Said was named as his successor in a smooth transition.
In a televised speech, Haitham promised to uphold Muscat's policy of peaceful coexistence and friendly relations with all nations while further developing Oman. "We will continue to assist in resolving disputes peacefully," he said.
According to the Omani constitution, the royal family shall, within three days of the throne falling vacant, determine the successor.
The high military council, in a statement carried on state media on Saturday, called on Oman's ruling family council to convene to choose a new ruler.
If the family does not agree on a name, the person chosen by Qaboos in a letter addressed to the royal family will be the successor.
The sultan should be a member of the royal family, as well as "Muslim, mature, rational and the legitimate son of Omani Muslim parents".
Qaboos transformed the Arabian Peninsula nation from a backwater into a modern state while pursuing a moderate but active foreign policy.
Having played a role in Iran's nuclear deal with world powers while preserving its membership in the Saudi-led Gulf Cooperation Council, Oman has emerged as the Gulf's discreet mediator.
It remains to be seen whether the next ruler will take the same moderate approach in a region often in turmoil.
Prime Minister Narendra Modi on Saturday condoled the demise of Sultan Qaboos bin Said al Said of Oman, describing him as a beacon of peace for the region.
"I am deeply saddened to learn about the passing away of His Majesty Sultan Qaboos bin Said al Said. He was a visionary leader and statesman who transformed Oman into a modern and prosperous nation," Modi wrote on Twitter.
Sultan Qaboos was a true friend of India and provided strong leadership for developing a vibrant strategic partnership between India and Oman, the prime minister said.
"I will always cherish the warmth and affection I received from him. May his soul rest in peace," Modi said.
The prime minister also said the Sultan was a beacon of peace for the region and the world.
(With inputs from AFP and Reuters)
