More than two million faithful will launch the annual Muslim pilgrimage here under heavy security imposed by Saudi authorities determined to crush any disturbances sparked by US threats to attack Iraq.The journey of faith will get under way in the early hours of Sunday when pilgrims make their way on foot to the Mina valley to begin the sacred rituals.An estimated 1.3 million pilgrims from 170 countries had arrived by Tuesday according to official figures, with the final number expected to reach two million.

Saudi authorities have taken extra security precautions this year amid heightened regional tensions as the United States pursues a military buildup in the Gulf ahead of a possible attack on Iraq, a Muslim nation and Saudi Arabia's northern neighbor.

Washington has threatened to invade and occupy Iraq unless President Saddam Hussein agrees to identify and destroy weapons of mass destruction that the United States says he is hiding.

Saudi Interior Minister Prince Nayef bin Abdull Aziz has vowed that his government will crack down on troublemakers during the pilgrimage and confirmed that security had been beefed up because of war preparations in the region.

"We will not allow any person or party to disrupt the security of the hajj (pilgrimage)," Prince Nayef said after inspecting security preparations at holy sites around Mecca.

"Our hand is strong and decisive."

Tens of thousands of police, security personnel, soldiers and national guardsmen are being deployed at the major sites on the outskirts of the city.

Authorities have also mobilized some 60,000 emergency staff and volunteers, including 5,000 firemen and medical specialists.

Nine helicopters will monitor the proceedings, which will also be scrutinized by 2,000 cameras linked to a hi-tech security operation room.

Organizers have erected 44,000 air-cooled and fireproof tents where pilgrims will spend the night before climbing Mount Arafat, 12 kilometers (eight miles) south of here, on Monday for the climax of the hajj.

After ascending Mount Arafat, pilgrims stop at the sacred site of Muzdalifa on Monday night and then head back to Mina where they must sleep the following three nights.

In Muzdalifa, 10 kilometers (six miles) south of Mecca, men dressed in a two-piece, white seamless cloth known as Ihram and women fully covered except for their faces will collect small rocks to throw at stone pillars representing the devil.

In Mina, in line with Islamic tradition, the faithful hurl the rocks, known as "jamarat," at the three pillars each about 18 meters in height (58 feet).

The ritual in principle lasts three days, and each pilgrim must throw seven stones on the first day at the main pillar, and then seven stones at each of the three pillars on the subsequent two days.

Also in Mina, pilgrims sacrifice an animal, normally a sheep, marking the first day of the Al-Adha feast of the sacrifice, which falls this year on Tuesday.

In the course of the pilgrimage the faithful in addition visit the Grand Mosque of Mecca, in the center of which is a structure known as the Kaaba, which Muslims believe to have been built by Abraham and his son Ismail.

They walk seven times around the Kaaba, one corner of which is a black stone that is said to have fallen from heaven.

In the wake of stampedes in 1994, 1998 and 2001 that claimed a total of 423 lives, authorities have drawn up a timetable for different delegations to complete the ritual.

Among those who have already arrived here, 200,000 are from Indonesia, the world's largest Muslim country, 130,000 from Pakistan, 116,000 from India, 103,000 from Turkey, 91,000 from Iran and 88,000 from Egypt, according to official figures.

PHOTO CAPTION

Saudi man looks at Muslim pilgrims gathering near the holy Kaaba