Muslim pilgrims retrace prophet's path as haj starts

There have been clashes between police and Iranian pilgrims in the past over political slogans. Sectarian tensions have arisen recently in the Arab world after Shi'ite Muslims came to power in Iraq, emboldening Iran and its Shi'ite allies.

Disputes between Palestinian factions Hamas and Fatah delayed and prevented some Palestinian pilgrims from arriving, adding another potential flashpoint.

Speaking in Mecca, Palestinian President Mahmoud Abbas blamed Hamas. "Unfortunately, this is the first time in the history of the Palestinian people that pilgrims were prevented. Israel never once prevented pilgrims," he told reporters.

The Saudi government is also wary of militancy. Despite an al Qaeda campaign to destabilise Saudi Arabia from 2003 to 2006, The haj has never been targeted by al Qaeda militants.

Islamist militants rampaged through the Indian financial capital of Mumbai last week, killing 171 people.

(Additional reporting by Nael al-Shyoukhi)