KABUL -- Frightened Afghans braced on Thursday for possible U.S. retaliation for devastating terror attacks on New York and Washington as Arab residents fled the capital or began digging trenches on the outskirts of the city. With U.S. investigators increasingly convinced that Saudi-born dissident Osama bin Laden was behind the attacks, many Afghans fear it is just a matter of time before they are made to pay for the ruling Taliban giving him sanctuary. The United Nations has begun pulling its staff out of Afghanistan in the wake of yesterday's attacks on the United States. In Geneva, UN spokeswoman Marie Heuze said that the move was a temporary precaution "due to circumstances prevailing internationally".

The mothers of the two American aid workers were planning to leave the country, fearing yesterday's attacks could prompt an assault by American forces here. At least four German aid workers were also hoping to leave. Up to 80 international employees are based in six Afghan cities - Kabul, Jalalabad, Mazar, Kandahar, Herat and Faizabad. The relocation began today and is expected to be completed by tomorrow, a UN statement said. "United Nations humanitarian agencies hope that activities can continue as normal so that critical pre-winter relief work can be completed," said the statement.

While it was not immediately clear how many Arab nationals live in Afghanistan, residents said almost all had left central Kabul. Afghan-Arabs -- a term encompassing virtually all non-Afghan Muslim militants regardless of their origin -- were also reported to have evacuated their bases elsewhere in the country. Muslim militants from the Middle East, Philippines, Central Asia and China have long used Afghanistan as a training base. The U.S. has previously described the country as a ``school for terrorism.'' With Washington vowing a ``hammer of vengeance'' to those responsible for the attacks and any country which aided them, the Taliban have been swift to deny responsibility.

But there was little sympathy from bin Laden himself. An aide, who spoke by satellite telephone to Abu Dhabi television in Pakistan, quoted him as saying that while he had nothing to do with the attacks, they were ``punishment from Allah.'' ``I have no information about the attackers or their aims and I don't have any links with them,'' the aide quoted bin Laden as saying. Kabul residents said they had seen people digging trenches on the outskirts of the city and that other fortifications were also being made. With television banned, Kabul residents could be seen with small transistor radios pressed to their ears listening to foreign broadcasts for news of the disaster.

The capital has already come under fire this week, after anti-Taliban forces used helicopter gunships to raid the city's airport in retaliation for an assassination attempt -- in which bin Laden was also implicated -- on its military commander. Despite growing fears, the Afghan capital remained largely calm on Thursday with markets and bazaars bustling as normal. But residents said they were frightened and scared, and most saw retaliation as a matter of course. One resident was pragmatic about any impending danger. ``I don't care about U.S. attacks,'' said government employee Shakir Ullah. ``I lost half my life in the noise of artillery, helicopters and fighting.''

With the specter of military strikes looming, diplomats from Australia, Germany and the United States -- in Kabul with a number of relatives of eight Christian aid workers on trial for promoting Christianity -- left for Pakistan. ``We did not sense any difference than any other day,'' U.S. diplomat David Donahue said on arrival. ``There was nothing going on in Kabul. It was quiet when we left.'' The plight of the eight has been enormously complicated by the U.S. terror attacks, and Donahue said the Taliban would be held responsible for the security of the detained foreigners.

Pakistan's military ruler General Pervez Musharraf responded unequivocally on Thursday to a U.S. request for support, promising full cooperation. ``All countries must join hands in this common cause,'' he said in a statement and on national television. ``I wish to assure President Bush and the U.S. government of our fullest cooperation in the fight against terrorism.'' Washington has vowed to strike back with a ``hammer of vengeance'' against those responsible for the attacks, which saw two hijacked commercial jets slam into the twin towers of New York's World Trade Center while another hit the Pentagon.

It was the worst attack on the United States since Pearl Harbor. But the Taliban warned retaliatory U.S. strikes would succeed only in sowing hatred in the region. ``If innocent and sinless people suffer, then it is certain that on the level of the region, hatred will further increase, the result of which will be similar to the suicide incidents,'' Taliban spokesman Abdul Hai Mutmaen told Reuters from the southern Afghan town of Kandahar.

Experts said that besides bin Laden -- who honed his guerrilla skills against Soviet troops in the 1980s commanding Arab fighters funded by the U.S. Central Intelligence Agency -- few have the cash or expertise to mount such attacks. The 44-year-old commands Islamic militants willing to die attacking the ultimate enemy, the United States, which has earned him a $5 million bounty on his head...