Saudi Arabia said on Saturday that stormy winds knocked over the crane which collapsed onto one of Islam's holiest shrines in Mecca and killed 107 people on Friday.
"Heavy rain and strong winds of unusually high speed led to the uprooting of trees, the fall of panels and the collapse of the crane," General Suleiman al-Amr, director general of the Civil Defence Authority, told Saudi-owned Al Arabiya TV on Saturday.
The number of deaths may increase, al-Amr said. Many of the 238 people injured in the accident were only lightly wounded, he said.
Mecca's governor, Prince Khaled al-Faisal, has ordered an investigation into the incident, Al Arabiya said.
Much of the city centre is undergoing construction work and many high cranes crowd the skyline. The Grand Mosque itself is undergoing an expansion and renovation.
The disaster was the latest in a series of deadly mishaps to hit the haj, one of the world's largest religious gatherings, after hundreds of pilgrims died in a stampede in 2006.
Authorities have broadened access paths and imposed limits on the millions of Muslims who converge on Mecca to perform the annual rite in an attempt to reduce accidents.
An unnamed Saudi official involved in organising the haj was quoted by Al Arabiya as saying the pilgrimage would go ahead as planned.
"The incident won't affect the haj pilgrimage this year and repairs to the damaged section (of the mosque) will begin within days," the official said.