The pilgrims are to spend Sunday praying at Mount Arafat where Mohammed gave his final sermon, the Financial Times reported. Monday is Eid Al-Adha, the Feast of Sacrifice, when pilgrims throw stones at rock pillars representing the devil.

The increasing number of people -- about 2.5 million this year -- creates huge logistical and security problems.

Prince Nayef bin Adel Aziz, the Interior Minister, told the Financial Times that about 100,000 police officers are on duty.

"We have heard of no special threat, but we must prepare ourselves and assume anything could happen," he said. "Terrorism is not over, but we are capable of facing any security threat or emergency.''

Safety is a big problem. Two years ago, 362 people were crushed to death during a stampede, and in 1990 a tunnel collapse killed 1,426.

Saudi Arabia has spent about $1 billion on improvements, including fireproof tents, new levels on bridges and enlarging the Grand Mosque.