Yesterday the Saudi police began to round up an estimated 200,000 illegal foreign workers who have overstayed a three-month departure deadline. Two-thirds of them are from India, Pakistan and Bangladesh, while the remaining third come from African countries.
If detained without valid travel documents and bookings they could be fined as much as $27,000, or serve six months in prison.
The round-up marks the end of a campaign to reduce the Saudi foreign workforce of nearly seven million, half the population of the kingdom, by 700,000.
The Saudi authorities expelled one million such illegals five years ago.
As those expulsions followed the 1991 Gulf war, the implication was that these people were somehow subversives, which was not the case then or today.
They are simply people desperate for work and excluded from the Saudi or Gulf labour markets because they do not have the necessary local sponsors to secure jobs legally.
Saudi Arabia attracts two types of illegal worker. First, a small number of labourers, mainly from the subcontinent, who sign on with subcontinent-based contractors for employment which is not officially sanctioned by the government.
Second, a much larger number of job-seekers who, following the annual pilgrimage to Mecca and Medina, the Haj, find work in the kingdom with Saudi contractors prepared to hire illegals.
Such employers avoid the complicated and lengthy procedures for legal recruitment, and also pay their workers less than the going rate.
Since the authorities seem to crack down on illegal workers only every five years or so, it suits the illegals, who secure jobs for a defined period with the expectation of making themselves indispensable and being taken on legally.
It also suits Saudi employers who profit from cheap labour, the Saudi authorities who accommodate influential businessmen, and the illegals' home governments, which benefit from the inflow of foreign currency.
But when the number of illegals climbs, they are expelled and the process begins anew.
The current crisis has arisen because of the pilgrims, who have stayed on beyond their pilgrimages over the last five years, perhaps at a rate of 100,000 a year.
They are granted entry on haj visas, allowing them to travel only to Mecca and the nearby area and to Medina, where the Prophet Muhammad is buried.
On arrival in Saudi Arabia all pilgrims surrender their passports and travel documents. These are returned on departure.
Therefore, when job-seeking pilgrims leave the Haj locations and enter the kingdom of Saudi Arabia proper, for which they have no visas, they become undocumented illegals. To depart, they must obtain new passports from their own governments, which is why certain consulates were besieged last week.
The illegals must then secure exit visas from the Saudi authorities. These can take great deal of time and a substantial cash payment to acquire.