United Nations efforts to send food to 700,000 Afghans gathered near Iran are being frustrated by Afghan lorry drivers, who have hidden vehicles for fear of American attacks, a senior UN official said.
Marius de Gaay Fortman, the World Food Programme (WFP) representative in Iran, said stocks of food inthe Taleban-controlled city of Herat were expected to run out this week.
Unless more can be sent quickly, the UN and Iran fear an exodus of refugees towards the nearby border.
Long before the attacks on America, the WFP was supplying nearly 8000 tonnes of food a month to Afghans driven to Herat by civil war and a severe drought.
Many Afghans living near Herat are ethnic Tajiks, who prefer Iran as a safe haven.
UN staff in Herat say their warehouses are secure, but almost empty.
The WFP is urgently trying to organise food convoys from Iran and is confident that Iran and the Taleban will allow the lorries through.
"If we had trucks, we have 3000 tonnes of American food ready to go, and 60,000 tonnes of aid easily available in the region," said Mr de Gaay Fortman.
"The main hiccup is to find Afghan drivers prepared to take it."
Food would be unloaded at the Iranian border and then put on Afghan transport.
"My people in the field tell me Afghan drivers are hiding their vehicles in safe places and are not so interested in business.
"I think they are scared their trucks will be damaged.
"My experience is that, even in a war area, you still see trucks going backwards and forwards. But usually you are dealing with two factions fighting on the ground and the drivers can buy their way through."