Heavy clashes erupt between Taliban and anti-Taliban group in Afghanistan's Panjshir province

Afghan resistance movement and anti-Taliban forces conduct military training at the Malimah area of Dara district in Panjshir province on September 2.

(CNN)Fighting in Afghanistan's last major holdout against Taliban rule continued through Friday after heavy clashes erupted overnight between Taliban fighters and an anti-Taliban group, according to Taliban sources.

Panjshir Valley, a mountainous, inaccessible region north of Kabul, has a long history of resisting the insurgent group. In the late 1990s, it was a center of resistance against the Taliban during their rule.
Now the National Resistance Front (NRF), a multi-ethnic group that includes former Afghan security force members and reportedly numbers in the thousands, has continued the fight against the Taliban following the militants' almost-complete takeover of Afghanistan.
    Sporadic fighting between the NRF and the Taliban has continued for two weeks now. The Taliban have been massing forces in and around Panjshir province in recent weeks, and said on Monday they had captured three districts in the valley.
      An NRF commander in Panjshir Valley said fighting was taking place around the Shatal district of Panjshir. The commander said NRF forces had inflicted hundreds of casualties on the Taliban. The Taliban denied these claims.
      A Taliban source said the militants attacked Panjshir from multiple directions, including from nearby Parwan province and the northern Badakhshan region.
      CNN has been unable to independently verify the overall casualty figures in the latest round of fighting, which also flared in provinces neighboring the Panjshir valley. Taliban video reviewed by CNN appeared to show its fighters in a gorge in the Shatal region, on the southwestern end of the valley.
        The NRF commander claims the Taliban threatened civilians and took hostages, warning residents they can be killed for supporting the resistance.
        Anti-Taliban forces take part in military training in the Panjshir Valley, the last major holdout against Taliban rule, on Thursday.
        Amrullah Saleh, a former Afghan vice president who joined the anti-Taliban fight, claimed on Twitter the Taliban "blocked humanitarian access to Panjshir" and forced military-aged men to walk minefields to clear them.
        The Taliban "have shut phone, electricity and [are] not allow[ing] medicine either," Saleh said.
        In official statements, the Taliban said they seek a negotiated end to the fighting and want Panjshiris to live in peace, highlighting their offers of amnesty to forces once aligned with the country's former US-backed government.
        Former Afghan President Hamid Karzai, who remains in Afghanistan, called on both sides to end the fighting.
        "Unfortunately, in recent days, despite the efforts of the reformers, military operations and fighting have started in Panjshir, which is a matter of deep concern and I do not consider the consequences to be in the interest of the country and the people," Karzai said in a statement. "That is why I call on both sides that war is not the solution for an Afghanistan that is wounded and suffering."

        Epicenter of guerilla warfare

        The overnight clashes between the Taliban and the NRF started late Thursday, and were very intense, said an NRF source. "They (Taliban) are using their last power to get in, but clashes are still ongoing," the source added.
        The anti-Taliban forces in Panjshir Valley includes  local resistance forces as well as remnants of the former Afghan army.