The veteran ruler of the United Arab Emirates, Sheikh Zayed bin Sultan al-Nahyan of Abu Dhabi, has died.
Sheikh Zayed had been president of the UAE since 1971
An announcement on Abu Dhabi television said the 86-year-old sheikh had died on Tuesday evening.
His death was not unexpected following recent rumours of his ill health, but correspondents say he will be greatly missed by people in the country.
His son, Sheikh Khalifa bin Zayed Al Nahyan, is expected to be elected as the new president.
The seven rulers of the Emirates will meet within 30 days to choose a successor.
In the meantime, the ruler of the emirate of Dubai, Sheikh Maktoum bin Rashid, will act as president.
The BBC's Julia Wheeler in the UAE capital, Abu Dhabi, said there was a subdued atmosphere and feeling of sadness among people as news of the sheikh's death became known.
Radio and television stations broadcast recitals from the Koranic verses, and schools, ministries and businesses are expected to close for several days as a 40-day period of mourning begins.
No cause of death was given, but the sheikh had a kidney transplant in 2000 and was recently in London for hospital treatment.
Born in 1918, fourth son of ruler of Abu Dhabi
Took power from his brother in 1966
President of UAE since foundation in 1971
Sheikh Zayed had been president of the UAE since its birth in 1971, and was a traditional figurehead.
He had not attended Arab summits for several years, but was known for trying to steer his country away from confrontation.
He had ruled Abu Dhabi - the richest and largest of the seven emirates and the capital of the state - since 1966, and named his son crown prince three years later.
Correspondents say the succession of Sheikh Khalifa as UAE president is likely to be a smooth affair, although they point out he is not such a strong unifying figure as his father, and there is a possibility of long-dormant rivalries reigniting.
The UAE was created in 1971, when six desert sheikhdoms - Abu Dhabi, Ajman, Dubai, Fujairah, Sharjah and Umm al-Qaiwain - gained independence following the departure of British troops.
The seventh emirate, Ras al-Khaimah, joined in 1972.
Under Sheikh Zayed's rule, with the massive income generated by its oil production, the country was transformed from a tribal backwater to a world financial centre.
The head of state stayed true to his desert roots, spending much of his time on falconry and other traditional Bedouin pursuits.
He was genuinely loved and respected by his citizens, who credited him with distributing wealth fairly throughout the country.
The sparsely-populated UAE has oil reserves of nearly 100bn barrels, or about 9% of the world's total.
Its four million inhabitants have one of the richest per capita incomes in the world and expatriates make up more than 85% of the population.