Northern Alliance troops, with their distinctive pakool caps, were seen entering Kabul from the north in jeeps and four-by-four vehicles early this morning. Taliban forces are reported to have fled the city.
The opposition forces made important gains yesterday to come close to securing the last northern stronghold of the Taliban, Kunduz.
The Northern Alliance last night were claiming to have taken the cities of Herat and Zaranj.
The opposition successes in the last 72 hours and reports from Kabul of fleeing Taliban have raised the real possibility that, despite concerns in the international community, the capital could fall to the alliance, while the Taliban regroups, presumably for a final stand, around their religious capital of Kandahar in the south.
Last night, the UN appealed to Afghan opposition leaders to meet within days to discuss a post-Taliban interim arrangements for the Afghan capital and to provide the nucleus for a broad-based government to replace the Taliban.
Mr Lakhdar Brahimi, the UN envoy who has been trying to reconcile Afghan factions, said: "We are going to try as soon as possible to get hopefully a representative sample of the Afghan population together and see what kind of interim arrangements we can work together for Kabul."
UN forces from Muslim countries such as Turkey, Bangladesh and Indonesia could help the Afghan politicians reimpose order in Kabul if the ruling Taliban collapse, but the United Nations would play mainly a supporting role, diplomats said.
"Our troops are knocking at the doors of Kabul. They are waiting to enter Kabul," the Northern Alliance spokesman, Mr Ashraf Nadeem, said by satellite phone from Mazar-e-Sharif earlier.
Reporters with the alliance recorded advances, backed by heavy US bombing and opposition artillery barrages, of several miles towards the city on several fronts.
"We have advanced five kilometres from Bagram airport," Gen Baba Jan said.
His bodyguard said 1,300 Taliban fighters at a village overlooking the airbase, to the north of Kabul, had surrendered, and many others had been killed.
Witnesses in the capital reported dozens of Taliban vehicles leaving on the Kandahar road to the south-west while for the first time the intelligence department was in darkness. A spotlight at its door that is lit from dusk to dawn had been switched off.
The house of the chief justice was also in darkness and his guard was not in his kiosk outside.
The Taliban deployed tanks at major roads leading into the capital in anticipation of an all-out assault from troops said to be within six to eight miles away.
The developments gave added urgency to talks in New York at the UN of the "six plus two" group, frontline states plus the US and Russia, about how to set up a broadly-based post-Taliban government.
There is concern that the largely Tajik and Uzbek alliance forces who are widely remembered and feared by the predominant Pashtun for their shelling of the city in the 1990s would be unable to prevent looting and retribution - indeed there were unconfirmed UN reports yesterday from a "volatile" Mazar-e-Sharif of abductions of civilians and summary executions.
There were also reports that hundreds of pro-Taliban Pakistani fighters have been systematically massacred in the city after being callously abandoned by retreating Taliban fighters, sources suggested last night.
Opposition fighters seized a UN aid convoy on Saturday, and a UN food warehouse had been looted.
