Unprecedented security measures protected the 1.7 million pilgrims who flowed in a sea of humanity across the plain of Arafat to pray for forgiveness on the Mount of Mercy (Jabal al-Rahma).

However little has so far disturbed the pilgrimage and yesterday the masses travelled from Mina, outside Makkah, some seven kilometers (4.5 miles) to Arafat, many walked but others took buses and pick-ups, to the pilgrimage's most important site.

"Here I am Allah, answering your call; there is no God but you," the pilgrims, all dressed in white, chanted as they approached Arafat.

Standing on Arafat before sunset on Saturday is the high point of the hajj, and pilgrims who fail to make it here on time must repeat their pilgrimage in future.

Many pilgrims headed straight for the 70-meter (230-foot) high Mount of Mercy, where they prayed for mercy in a symbolic re-enactment of Prophet Mohammed's only pilgrimage.

Pilgrims spend the day imploring forgiveness and beseeching God for success before returning to Mina to sacrifice an animal, generally sheep, marking Eid al-Adha, or Feast of the Sacrifice, which starts here on Monday.

The interior ministry said Friday that 1,419,706 pilgrims had come from abroad, 16,083 less than last year.

Hajj Minister Iyad Madani said they were expected to be joined by some 250,000 pilgrims from within Saudi Arabia, in addition to faithful from among Mecca residents.

The authorities, who have warned they will not tolerate any attempt to undermine security, are working overtime to prevent any attacks in the kingdom during the pilgrimage.

Six Saudi security men were shot dead Thursday as they searched for arms and explosives in a wanted militant's home in Riyadh, 700 kilometres (435 miles) from Makkah. The militant was arrested in the operation, and his father killed.

The interior ministry said security forces in the capital subsequently arrested seven suspected members of a group planning a "terror attack" and seized large amounts of arms and explosives.

Security forces arrested "seven individuals suspected of belonging to the group... preparing a terror attack," said an interior ministry statement quoted Friday by the official SPA news agency.

Raids on two Riyadh hideouts of presumed Islamist militants Thursday night netted a booby-trapped car and 21 explosives belts among large amounts of arms and explosives, the statement said.

The security operation followed the fatal shooting, also Thursday, of six security men and the father of a detained suspect during a search of his home.