Saudi Arabia's King Abdullah bin Abdulaziz has been buried at the El-Ud public cemetery in Riyadh.

Earlier on Friday, Turkish President Recep Tayyip Erdogan, Pakistani Prime Minister Nawaz Sharif, Sudanese President Omar Hassan al-Bashir and Egypt’s Prime Minister Ibrahim Mehleb joined the leaders of Gulf Arab states for the funeral prayer at the Imam Turki bin Abdullah mosque.

Bahrain's King Hamad Bin Isa Al-Khalifa, Qatari Emir Sheikh Tamim Bin Hamad Al-Thani, a high-level delegation from the United Arab Emirates and Kuwait's Emir Sheikh Sabah Al-Ahmad Al-Sabah were at the funeral, state television showed on Friday.

Earlier, a royal court statement said that the king, believed to be around 90, had died at 1:00am local time (22:00 GMT), expressing its "great sadness and mourning".

The officials did not disclose the cause of King Abdullah's death, but he was admitted to hospital in December suffering from pneumonia and had been breathing with the aid of a tube.

In keeping with the kingdom's traditions, the king was buried in an unmarked grave as was his predecessor King Fahd, who died in 2005.

Al Jazeera's Hashem Ahelbarra said: "This is someone who is definitely going to be remembered as a reformist within the royal family.

"He succeeded his brother at a very delicate time and started reforms in the country."

Crown Prince Salman bin Abdulaziz al-Saud, the deceased king's half-brother, has officially been named as the next ruler of the world's top oil exporter and the spiritual home of Islam.

Saudi Arabia's Western and Arab allies, along with countries such as Israel and China, offered their condolences on the death of the king.

King Salman, 79, in his first public address, pledged no change in the kingdom's direction and called for unity among Muslims.

"We will remain with God's strength attached to the straight path that this state has walked since its establishment by King Abdul Aziz bin al-Saud, and by his sons after him," Salman said his in televised remarks.

Prince Muqrin Bin Abdulaziz has been announced as the new crown prince, state TV announced.

The new king also appointed his nephew Mohammed bin Nayef as deputy crown prince, meaning he will be the first person of the next generation to rule the kingdom one day.

Prince Mohammed, who remains as interior minister, according to the royal decree carried on state television, is next in line to rule after Salman and Crown Prince Muqrin.

Obama condolences

US President Barack Obama offered his condolences on King Abdullah's death.

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

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

King Abdullah, thought to have been born in 1923, took the throne in 2005, but had run the country as de facto regent for a decade before that after his predecessor King Fahd suffered a debilitating stroke.

At stake with the appointment of Salman as king is the future direction of the US' most important Arab ally and self-appointed champion of Sunni Islam at a moment of unprecedented turmoil across the Middle East.

Most recently, the kingdom joined the US-led coalition carrying out air strikes against the Islamic State of Iraq and the Levant.

King Abdullah played a guiding role in Saudi Arabia's support for Egypt's government after the military intervened in 2013, and drove his country's support for Syria's rebellion against President Bashar al-Assad.

King Salman has been crown prince since 2012 and has been heading the defence ministry since 2011. He was governor of Riyadh province for five decades before that.

Source: Al Jazeera and agencies