Saudi Crown Prince Nayef bin Abdel Aziz hailed the "success" of this year's hajj despite the risk of "chaos" feared in the wake of the Arab Spring, state news agency SPA reported. "We thank God for the success of this year's hajj, which was the best pilgrimage season to ever pass," Nayef told the commanders of hajj security forces late on Tuesday. "Some (pilgrims) were expected to exploit the international and regional changes taking place to cause chaos. But thank God this did not happen," SPA quoted Nayef, who also holds the interior portfolio, as saying. The hajj -- the world's largest annual gathering -- this year coincided with the Arab Spring democracy protests that have swept many nations in the region and led so far to the unseating of three autocratic leaders in Tunisia, Egypt and Libya. The conservative Sunni kingdom itself had been slightly touched by the unrest as Shiites held sporadic protests in its Eastern Province a few times over the past months. 'But their movement was quickly contained by Saudi authorities. "We thank all the pilgrims for proving that they are Muslims who respect this (hajj) rite and for being cooperative," the prince said. Saudi security forces have several times in the past confronted Iranian pilgrims holding anti-US and anti-Israeli protests. In 1987, Saudi police efforts to stifle such a demonstration sparked clashes in which 402 people died, including 275 Iranians. But no incidents were reported this year as Iranian pilgrims, put at around 97,000 --- the maximum allowed for Iran under a Saudi system apportioning pilgrim quotas among the world's biggest Muslim countries -- held their protests inside their own camps on Saturday. Already strained ties between Iran and Saudi Arabia became taut last month when the United States accused Iranian officials of having a hand in a thwarted plot to kill the Saudi ambassador to Washington. Iran has strongly denied involvement and emphasised "good relations" with its Arab neighbour across the Gulf. Most of this year's three million Muslim pilgrims had left the holy city of Mecca after they performed the final rituals of the hajj on Tuesday. Others will continue the last rite of the annual pilgrimage -- stoning of the devil -- on Wednesday.