But for reasons no one entirely understands, the number of prostitutes on the streets of Iranian cities and towns has grown substantially in recent years, particularly in Tehran and the holy city of Qom, which is a center for pilgrims and domestic tourists.

Prostitutes wear their veils loosely over their heads in a style that passes for risque in this strictly regulated society. With their faces heavily made up, they stand at traffic circles where men driving by can inspect them and make a deal. The women are often young, including many teenagers who have run away from abusive homes.

Based on official figures, there are some 300,000 women who work as prostitutes in Iran. And according to newspapers, the number is steadily rising, despite frequent police crackdowns.

The temporary marriage license would protect the couple from harassment by authorities and, according to some proposals, it would be accompanied by free contraceptives and health advice. Under religious law, a temporary marriage imposes no obligations on a man unless the union produces a child, who must be recognized as legitimate and can claim a share of any inheritance.

One cleric backing the plan, Ayatollah Mohammed Mousavi Bojnurdi, recently told a newspaper: "We face a real challenge with all these women on the street. Our society is in an emergency situation, so the formation of the chastity houses can be an immediate solution to the problem." He added that the plan "is both realistic and conforms to Sharia [Islamic] law."