Some 4,000 to 5,000 Afghans are fleeing into Iran each day using informal border crossings to escape Taliban rule, the Norwegian Refugee Council (NRC) said Wednesday. 

Since the fall of the Afghan government and chaotic withdrawal of US forces in August, an estimated 300,000 Afghans have crossed the border into neighboring Iran, the aid agency said. NRC expects the numbers to rise by hundreds of thousands as Afghanistan’s harsh winter approaches and its humanitarian crisis intensifies. 

“Iran cannot be expected to host so many Afghans with so little support from the international community,” NRC Secretary General Jan Egeland said in a statement. “There must be an immediate scale-up of aid both inside Afghanistan and in neighboring countries like Iran, before the deadly winter cold.”

Afghan refugees are considered the third-largest displaced population in the world, with 90% of those who fled living in Iran and Pakistan. According to the United Nations’ refugee agency, Iran hosts some 3.6 million Afghans, roughly 780,000 of whom are formally registered as refugees.