Eyewitnesses say Taliban military forces appear to have deserted the capital of Kabul at dawn Tuesday, following a series of swift military victories by opposition forces over the past four days, several news agencies are reporting.

Sporadic small arms fire from hills overlooking the city could be heard but the streets were empty of the Taliban soldiers, who had been there hours earlier.

Opposition forces began moving into Kabul on Monday night, despite warnings from Washington to refrain from entering the Afghan capital.

Northern Alliance tanks roll into the town of Taloqan

Shouting "God is Great," and with pictures of slain military leader Ahmed Shah Masood on the side of their trucks, opposition fighters made their first significant advances toward the city since the U.S. air campaign began more than five weeks ago.

"We will not enter Kabul," said Abdullah Abdullah, the Northern Alliance foreign minister said earlier on Monday. "We will stop at a convenient front line."

Taliban soldiers fled their positions north of Kabul and were reportedly on the move to the southern city of Kandahar, bringing eight foreign aid workers with them.

The two Americans, four Germans and two Australians have been detained since August.

But Taliban ambassador to Pakistan Abdul Salam Zaeef denied reports the regime was abandoning the city. Instead, he said, the Taliban was reinforcing the capital.

Opposition troops flying the green-and-white flag of the Northern Alliance moved to within 20 kilometres of the city, and were fighting with Taliban forces near the air base at Bagram.

U.S. warplanes continued to pound Taliban targets in and around the capital. An American bomb heavily damaged a Kabul factory, killing at least one person.

A Northern Alliance spokesman said the anti-Taliban fighters had shored up their gains near Kabul, halting at Mir Bacha Kot. There, they are awaiting further orders.

At the same time, opposition forces claimed to have taken the western city of Herat, and were nearing the last Taliban stronghold in the north.

After holding less than 10 per cent of Afghan territory for months, the Northern Alliance made rapid gains over the weekend, and now says it controls almost half the country.

Displaced people rush to return to homes in Taloqan

On Monday, truckloads of displaced people followed Northern Alliance military vehicles into Taloqan, an area in northeastern Afghanistan that until recently was controlled by the Taliban.

To avoid landmines, they followed tank tracks to a destroyed Taliban outpost where they found a few burlap bags, water cannon and an old radio antenna.

The surprisingly fast advances by the Northern Alliance, beginning on Friday when they claimed the key northern city of Mazar-e-Sharif, have Washington worried they will overrun the capital.

On Saturday, President George W. Bush warned the Alliance against entering the city.

Bush and Pakistan's President Pervez Musharraf are worried that the Uzbek and Tajik dominated Alliance would not be welcome in the mostly Pashtun capital.

Musharraf said on the weekend he is worried that the city would be the site of bloody atrocities, as it was before the Northern Alliance was thrown out of Kabul by the Taliban.

The coalition against terrorism wants to have a political solution in place to set up a government that would represent all Afghan factions before the city is taken.

So far, the Northern Alliance leadership says it will comply with Washington's wishes, but some of the commanders on the ground are reportedly anxious to take the city.