Fierce fighting raged in northern Afghanistan yesterday as Taliban troops battled opposition forces.

The opposition forces were seeking revenge for the assassination of their leader, while taking advantage of the threat of US strikes.

The latest battle broke out on Thursday in a region south of Balkh and in Dara-i-suf in the neighbouring Samangan province, where the opposition Northern Alliance, headed by Burhanuddin Rabbani, reported the capture of several Taliban posts and dozens of villages, sources claimed.

There were also reports that the leader of Afghanistan's Uzbek minority, Gen Abdul Rashid Dostum, had concentrated a considerable force near the northern city of Mazar-i-Sharif to fight the Taliban.

With the world focusing on how the Taliban is responding to US demands to hand over the wanted fugitive Osama bin Laden, the puritanical Islamic movement's opponents have been stepping up their activities inside the country.

The US has vowed to hunt down bin Laden - who lives as a "guest" of the Taliban - and punish his protectors.

On Friday, the Northern Alliance said it had driven the Taliban out of Dara-i-suf, which lies on a strategic Taliban south-north supply line, but the Taliban had struck back with air power.

"After our victories, the Taliban have launched a massive counterattack with help of their air force, but so far they have not succeeded in regaining any of the lost grounds," spokesman Mr Ashraf Nadeem said. He spoke by satellite phone from within the 5 per cent of Afghanistan controlled by the opposition.

Mr Nadeem said dozens of Taliban fighters had been killed, while Northern Alliance casualties were put at four dead and 10 wounded. The figures could not be verified because of the remoteness of the region. The Taliban confirmed that fighting had erupted in the area but gave no details.

The Northern Alliance suffered a major blow last week when two suicide assassins posing as Arab journalists killed their military commander, Gen Ahmad Shah Masood.

The next day the US was hit by terrorist attacks. Bin Laden has been linked to both plots.

Russia's Itar-Tass news agency said Afghan Uzbek leader Gen Dostum had concentrated a huge force near Mazar-i-Sharif in the north. Gen Dostum rose through the ranks of the Afghan army after the Soviet Union invaded Afghanistan in 1979, and has switched sides several times as the country's government has changed.

His fighters were already involved in what the agency described as an effective "people's rebellion".

The report estimated his forces at 15,000, but this could not be independently confirmed.