The Taleban had captured the districts - Imam Sahib and Dashte Archi, both in Kunduz province - last week during a renewed offensive aimed at taking control of the entire country.

The opposition says there has also been heavy fighting for control of the fort of Sher Khan Bander on the Amu Darya river, which marks Afghanistan's northern border.

Independent sources confirm that Dashte Archi is now in alliance hands, but it has not been possible to confirm independently the status of Imam Sahib.

Major offensive

On Thursday, the Taleban withdrew to their original front lines about 25km north of Kabul, after their offensive in the Shomali Valley was repulsed.

The BBC's Kabul Correspondent, William Reeve, says that, since then, there have been exchanges of artillery fire between the two sides, with little change of positions.

The Taleban had moved north in an effort to reach the Panjshir Valley - stronghold of opposition chief Ahmed Shah Massood.

They say they still hold some high ground overlooking the key Bagram airbase, and hope to launch a counter-offensive soon.

UN condemnation

On Thursday, the UN Security Council called on the Taleban to end the offensive and resume talks with the opposition.

The council also urged other countries not to interfere.

It called on those states "whose territories are reportedly being used by Afghan parties, to take measures to prevent such acts".

The Taleban are often accused of having Pakistani support, while Taleban leaders say Russia, Iran, Tajikistan and Uzbekistan back the opposition alliance.