TEHRAN Millions of Afghans have headed for their country's borders with Iran and Pakistan following repeated threats from the United States of a possible attack on Afghanistan.

The U.S. has accused Saudi dissident Osama bin Laden of masterminding the Sept. 11 attack on New York's World Trade Center and the Pentagon.

The Taleban, Afghanistan's ruling party, is said to be harboring bin Laden.

Washington has given the Taleban militia three days to hand him over.

There are currently 2 million Afghan refugees seeking asylum in Iran, and an influx of millions more is expected in the very near future.

However, Iranian border officials have said that they will place the refugees in camps inside Afghan territory.

Quoted by IRNA, the official in charge of alien affairs in Khorasan Province, which borders Afghanistan, reiterated on Sunday that Afghan refugees would not be allowed into Iranian territory in the event that the United States launches retaliatory attacks.

"The Afghan nationals should stay on the other side of the border and should not consider entering Iran," Mohammad Olama told IRNA.

"We have ordered our border guards not to let any Afghan refugees enter Iran," he said, adding that Iran would provide humanitarian aid in Afghan territory for the would-be refugees.

Iran has called on the security forces along its eastern border with Afghanistan to seal off the 900-kilometer boundary in preparation for the consequences of probable U.S. retaliatory strikes.

Fearful Afghans began fleeing the country as their hard-line Taleban rulers vowed to wage war against anyone helping the U.S. launch attacks, and urged all Muslims to fight to their deaths.