Bamiyan has been fully liberated

Opposition spokesman Mohammad Alizadah

In a separate development, the Taleban ordered the United Nations to close its office in the capital, Kabul.

The move was in response to the closure of the Taleban office at the United Nations in New York, in line with sanctions aimed at forcing the Afghan authorities to hand over the Saudi-born dissident, Osama Bin Laden.

Two-pronged attack

Bamiyan fell to opposition fighters late on Tuesday after they launched an attack from two sides.

"Our forces entered Bamiyan city last night," Mohammad Alizadah, an opposition spokesman, said.

"Bamiyan has been fully liberated."

Dozens of Taleban soldiers are said to have died in the assault and its forces have now pulled outside the city limits.

"There are losses on our part. We have left behind a number of vehicles and arms as well," a senior Taleban official said according to the AFP news agency.

Sanctions

Last year, the ruling militia made several inroads into opposition-held areas, including the capture of key bases along the main supply route to the north.

Hundreds of thousands have been displaced

The Taleban captured Bamiyan in 1998 but have been under constant pressure from opposition forces led by Ahmed Shah Masood.

The latest fighting comes as tough, new United Nations sanctions on the Taleban started last month over their refusal to hand over Mr bin Laden.

The Taleban complain that the UN's unilateral arms embargo has encouraged the opposition to attack their positions.

Bamiyan is a significant gain for the opposition, but when they have captured similar places in the past, they have only managed to hold them for brief spells during the winter. Spring usually brings the return of the Taleban.

Hundreds of thousands of Afghans have been displaced by the ongoing war and are living in makeshift border camps, in life-threatening conditions.

UN officials have warned of a major disaster if emergency aid was not immediately made available to the refugees.