Some 2.5 million pilgrims are expected to make the Hajj
Individuals selected randomly and considered "suspicious" among the hundreds of thousands of Muslims arriving for the event will be taken aside to have their irises digitally scanned.
The machines have been installed in the King Abdul Aziz International Airport in the Red Sea port city of Jeddah, a Saudi official, speaking anonymously, told the Associated Press.
The US has publicly praised Saudi Arabia for its support in the US-led "war on terror", but there are fears that the huge Muslim gathering could be a recruiting ground for those in sympathy with al-Qaeda.
"Those suspected of being involved in terrorism activities will have their names listed at all entry ports," said Saudi official Lieutenant Colonel Ibrahim bin Saleh al-Hamdan.
One of Osama Bin Laden's stated objections is to the 5,000 US troops that share Saudi soil with some of the holiest sites of Islam.
And American investigators have said that 15 of the 19 hijackers in the 11 September attacks were Saudis, as were - according to the Saudi Government - 100 of the first 158 prisoners taken to Guantanamo Bay.
Tracking pilgrims
The hi-tech devices use a technique known as biometrics - recording individuals' unique physical features - to gather data which will enable the Saudi authorities to identify and track individual pilgrims.
The official said that the number of intelligence officers had been significantly increased for this year's annual pilgrimage.
Colonel al-Hamdan also said machines for detecting false passports had been installed.
These, together with the biometrics technology, will help the Saudis cut down immigration by visitors who do not return home after the pilgrimage.
Trip of a lifetime
Every able-bodied Muslim who can afford it is required to make the Hajj at least once in a lifetime.
An estimated 2.5 million people are expected to attend this year's rituals.
About 80% of those arriving from outside Saudi Arabia will travel through the King Abdul Aziz airport, which has a specially dedicated Hajj Terminal.
The government spends an estimated $1bn hosting the annual event and has an entire ministry responsible for its smooth running.
The Ministry of Pilgrimage estimates that 120,000 Pakistanis, 110,000 Indians and 92,000 Iranians will make this year's Hajj, which reaches its climax on 21 February with a visit to Mount Arafat.