°®Âþµº

Saudi Arabia's elderly King Abdullah died on Friday and was replaced by his half-brother Salman as the absolute ruler of the world's spiritual home of Islam.

Global leaders paid tribute to the king, who held power in through a period of regional instability, the Arab Spring uprisings and the rise of Islamic extremism.

The royal court said in a statement that Abdullah, believed to be about 90, died at 1am local time. It expressed "great

Under Abdullah, Saudi Arabia has been a key ally of Washington in the Arab world.

sadness and mourning".

Salman, 79, had been defence minister and previously governor of the capital Riyadh.

Another of the late monarch's half-brothers, Muqrin, was named crown prince.

Abdullah will be buried later on Friday following afternoon prayers, the statement said.

Citizens will then 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 has been in hospital since 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 attacks against the Islamic State group in Syria and Iraq.

In a written statement the US president, Barack Obama, said: "As our countries worked together to confront many challenges, I always valued King Abdullah's perspective and appreciated our genuine and warm friendship.

"The closeness and strength of the partnership between our two countries is part of King Abdullah's legacy."

Other tributes came in from Japan, India and France, whose President Francois Hollande hailed Abdullah as "a statesman whose work profoundly marked the history of his country".

Saudi Arabia is the top producer in the Opec oil cartel and has been the driving force behind its refusal to slash output to support oil prices, which have fallen by more than 50 percent since June.

Oil prices rose Friday following Abdullah's death, amid uncertainty over whether the new king would maintain that policy.

Wary of the rising influence of Islamist movements, Saudi Arabia has been a supporter of Egyptian leader Abdel Fattah al-Sisi since the army removed Mohammad Morsi, Egypt’s first freely elected president, who was a part of the Muslim Brotherhood. Riyadh has also supported rebel groups in Syria.

Abdullah pushed through cautious changes while in power, including appointing women to the Shura Council, an advisory body.

He promoted the kingdom's economic development and oversaw its accession to the World Trade Organisation, tapping into the country's huge oil wealth to build new economic cities, universities and high-speed railways.

But Saudi Arabia is still strongly criticised for a dismal human rights record, including the imprisonment of dissidents, capital punishment by beheading and gender inequality. It is the only country in the world that does not allow women to drive.

Te kingdom's suppression of free speech was highlighted in the final weeks of Abdullah's rule when Raef Badawi, a blogger, was sentenced to 1,000 lashes and 10 years in jail for comments made on social media.

Badawi's Twitter account reposted a comment on Abdullah's death saying: "God forgive him and have mercy on him."

Amnesty International said earlier that Saudi Arabia had postponed for a second time on medical grounds Badawi's flogging, which had been due to resume on Friday. He has already received 50 lashes.

Campaigners for women's right to drive referred only in passing to the king's death, saying on their Twitter account: "For all creatures big or small - nothing remains but your deeds and your grave - and only God lasts forever".

Challenges ahead

Salman, the new king, is not expected to diverge from the path of his predecessor. He is a stalwart of the royal family credited with transforming Riyadh into a thriving capital during his half-century as governor.

Salman is also in poor health but took on an increasingly high-profile role as Abdullah's condition worsened.

Abdullah named Muqrin as deputy crown prince last March, in an unprecedented move aimed at smoothing succession hurdles.

Muqrin, a former intelligence chief, was a trusted confidant of Abdullah with a reputation as a liberal, a relative term in Saudi Arabia.

A former air force officer born in 1945, Muqrin is the youngest son of King Abdul Aziz bin Saud, the founder of Saudi Arabia.

Since King Abdul Aziz's death in 1952 the throne has systematically passed from one of his sons to another.

Abdul Aziz had 45 recorded sons and Abdullah, Salman and Muqrin have different mothers.

The new king will face some major challenges, especially as falling oil prices cut into state revenues.

Saudi Arabia has tried to avoid the social upheaval that has shaken many of its neighbours in recent years, relying in large part to massive public spending.

But it still has to deal with discontent among a sizeable Shia minority as well as growing general unhappiness with the pace of reforms and economic disparities.

The country has amassed enormous financial reserves, but has already projected a huge deficit of $38.6bn this year.