Although the crossing here was of a mere 69 volunteers among the 202,000 Iraqi refugees estimated to be in Iran, the UNHCR hopes that if all goes smoothly thousands of others impatient to head home can do so legally and in relative safety.

UNHCR's representative in Iran, Philippe Lavanchy, told AFP the agency had to overcome "enormous difficulties" to get the operation underway.

Those problems largely relate to US accusations that Iran is seeking to undermine post-war security in Iraq, and fears a flood of returnees could include foreign fighters who US-led coalition forces allege are partially behind the country's worsening security problems.

All of Wednesday's returnees were from Ashrafi, the largest Iraqi refugee camp inside Iran situated near the southwestern city of Ahvaz -- just across the border from the Iraqi city of Basra.

Many have been there since fleeing the Saddam Hussein regime's waves of crackdowns on Shiite Muslims in the south of the country that followed an uprising after the 1991 Gulf War, and notably his draining of an area inhabited by the so-called Marsh Arabs.

In the absence of any formal repatriation process, many refugees have chosen to go it alone and cross the porous border illegally -- despite the high danger of landmines or the risk of being arrested by coalition forces.

UNHCR's task has also been complicated by the evacuation of its foreign staff from Iraq following a string of deadly bombings and attacks on the United Nations and other aid groups.

Surmounting simple logistical obstacles -- such as finding drivers and transport to carry them to Basra -- also proved complex here, with the crossing being held up here in Shalamcheh, a dusty post on the Iranian side of the border, for several hours of haggling and paperwork.

In the absence of foreign UN staff, Iraqis working for the agency met the returnees as they crossed the border, while a small British forces unit was also there to provide them with an armed escort along the short stretch of road to Basra -- another area where the UN has come under attack.

Each returnee was been given 20 dollars, a kit containing travelling essentials and mine awareness training.