Saudi Arabia's elderly King Abdullah has died and has been replaced by his half-brother Salman as the absolute ruler of the world's top oil exporter and the spiritual home of Islam.
Global leaders paid tribute to the late monarch, a cautious reformer who led his kingdom through a turbulent decade in a region shaken by the Arab Spring uprisings and Islamic extremism.
The royal court said in a statement that Abdullah, believed to be around 90, died at 1am local time on Friday, expressing its "great sadness and mourning".
Another of the late monarch's half-brothers, Muqrin, was named the new crown prince.
In his first public statement as the new ruler, the 79-year-old King Salman vowed to maintain a steady course for the conservative kingdom.
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"We will remain with God's strength attached to the straight path that this state has walked since its establishment," Salman said in televised remarks on Friday.
He called for "unity and solidarity" among Muslims and asked for God to support him in his "great responsibility".
Salman moved quickly to consolidate his hold on power, naming Interior Minister Mohammed bin Nayef as the new deputy crown prince and one of his own sons, Prince Mohammed, to replace him as defence minister.
Abdullah was to be buried later on Friday following afternoon prayers, with citizens then invited to pledge allegiance to the new monarch and the crown prince at the royal palace.
The royal court did not disclose the cause of Abdullah's death, but he was hospitalised in December suffering from pneumonia and had been breathing with the aid of a tube.
Under Abdullah, who took the throne in 2005, Saudi Arabia has been a key ally of Washington in the Arab world, most recently joining the US-led coalition carrying out air strikes against the Islamic State group in Syria and Iraq.
President Barack Obama was quick to pay tribute to Abdullah as a "valued" ally.
"The closeness and strength of the partnership between our two countries is part of King Abdullah's legacy," Obama said in a written statement shortly after the monarch's death.
Other tributes came in from foreign leaders, with French President Francois Hollande hailing Abdullah as "a statesman whose work profoundly marked the history of his country".
Several Middle Eastern dignitaries including King Abdullah II of Jordan and Saudi Arabia's Prince Turki al-Faisal al-Saud, the half-brother of Abdullah, left the Davos World Economic Forum early on Friday following news of the king's death.
Saudi Arabia is also home to Islam's holiest sites, Mecca and Medina, and its role as a spiritual leader for Sunni Muslims has seen it vying for influence with Shi'ite-dominated Iran.
Tehran nonetheless offered condolences over Abdullah's death, saying Foreign Minister Mohammad Javad Zarif would travel to Riyadh to take part in official ceremonies.
King Salman is widely expected to follow closely in Abdullah's footsteps, in foreign and energy policy as well as in making moderate reforms to the deeply conservative kingdom.
But Saudi Arabia is still strongly criticised for a dismal human rights record, including the imprisonment of dissidents.
It is also the only country in the world that does not allow women to drive.
