THE Iranian establishment heaved a sigh of relief on April 13 when a powerful students organisation called off a rally which had been credited with immense destabilising potential. The provocation for the threat was the arrest of Tehran's mayor Ghulamhussein Karbaschi, sparking off probably the biggest crisis in the Islamic Republic's almost 20-year history which has left the country sharply divided. Notes political commentator Darioush Sajjadi: "It's alarming because a controversy surfaced even among the top officials of the system."