RIYADH (Agencies) - World leaders, including President Asif Ali Zardari and Irans foreign minister, poured into Riyadh to offer condolences on the death of Saudi Crown Prince Sultan bin Abdul Aziz who was buried on Tuesday in the presence of an ailing King Abdullah. Chief of Army Staff General Ashfaq Parvez Kayani also attended the last rites of the Crown Prince. While his successor has yet to be named, the body of Sultan, who died on Saturday in a New York hospital, has been repatriated to Riyadh for the funeral. It is the first time that the heir to the thrones seat stays vacant in the history of the OPEC kingpin, where the monarchs advanced age and health issues have raised concern in a country ruled by the Al-Saud family since 1932. Ailing King Abdullah, 87, who arrived on a walker with a surgical mask on his face, remained seated as he took part in the funeral ceremony. The monarch was hospitalised for a new back surgery in Riyadh earlier this month, following two similar operations last year in the United States. Sultans body was wrapped in a brown cloth and laid on the mosque ground as the mourners prayed for him. It was then taken out of the mosque to be buried in a nearby cemetery. More than 100 world dignitaries have being gathering in the capital. Ali Akbar Salehi, foreign minister of Iran, the kingdoms arch foe, arrived for Sultans funeral, the Saudi news agency SPA reported. Tensions have risen between Iran and Saudi Arabia in the past two weeks, since US allegations surfaced that Iranian officials plotted to assassinate the Saudi ambassador to Washington. Although Tehran has rubbished the accusations, Riyadh has taken them seriously and said it was pondering a suitable response. Even before the plot claims, ties between the two regional rivals were strained over Saudi Arabias military assistance to Bahrain to put down pro-democracy protests by mostly Shia demonstrators. From Egypt - where protesters, backed by the army, ousted Saudi Arabias ally Hosni Mubarak earlier this year - military ruler Field Marshal Hussein Tantawi flew in for the funeral, Saudi state television Al-Ekhbariya reported. It is Tantawis first trip abroad since he took power in February with the downfall of president Mubarak. Jordans King Abdullah, whose government declared a day of mourning on Tuesday, also landed in Saudi Arabia, as well as Sudans President Omar al-Bashir, wanted by the International Criminal Court. Gulf leaders Sheikh Hamad bin Khalifa al-Thani of Qatar, Kuwaits Emir Sheikh Sabah al-Ahmad al-Sabah and Bahrains King Hamad bin Issa al-Khalifa were all present in Riyadh for the funeral of Sultan. SPA reported that Turkeys Deputy Prime Minister Bulent Arinc and Malaysian Prime Minister Najib Razak also joined the mourners in the Saudi capital. US Vice President Joe Biden was likewise among world leaders heading to the Saudi capital to offer condolences. Syrian Vice President Faruq al-Sharaa arrived in Riyadh as the Saudi news agency SPA reported that London-based Rifaat al-Assad, exiled uncle of Syrias President Bashar al-Assad, had flown in. Ties have soured between Saudi Arabia and Irans ally Syria, where the United Nations says more than 3,000 people, mostly civilians, have been killed since mid-March in a crackdown on dissent. Sultan was the second deputy prime minister until the then crown prince Abdullah acceded to the throne in 2005. Prince Nayef bin Abdul Aziz, a half-brother of King Abdullah and the kingdoms internal security czar who has held the interior portfolio for over three decades, is touted as the most likely heir to Sultan. King Abdullah, who is also the prime minister, in 2009 appointed Prince Nayef, 78, as second deputy premier, in a move interpreted as putting him in line for the throne. President Zardari was accompanied by Chief of Pakistan Muslim League-Quaid Chaudhry Shujaat Hussain, Interior Minister Rehman Malik and Chief of the Army Staff Gen Ashfaq Parvez Kayani.