The Taliban claimed on Monday to have captured the Panjshir Valley, the last bastion of Afghanistan not firmly under their control, even as representatives of the opposition forces there maintained that they still had control over strategic positions in the region and vowed to fight on.

       The conflicting accounts of what was happening on the ground in the region 70 miles north of Kabul were hard to verify as internet and telephone service into the region has been cut off.

       While rumors of the Taliban’s having taken over swirled this past weekend, it was not until Monday morning that the group officially claimed control.

       “Panjshir Province completely fell to the Islamic Emirate of Afghanistan,” Zabihullah Mujahid, the Taliban’s spokesman, wrote in a statement on Twitter.

       Taliban fighters posted images online said to be of militants raising the flag of the Islamic Emirate of Afghanistan, as the Taliban calls the country, in the provincial capital, Bazarak, as well as of their forces talking to local leaders.

       While the Taliban claimed that they had conquered the entire province, the opposition group, the National Resistance Front, disputed that account, saying that its forces were still positioned across the Panjshir Valley.

       “We assure the people of Afghanistan that the struggle against the Taliban and their partners will continue until justice and freedom prevails,” it said on Twitter.

       For its part, the Taliban sought to reassure the local population that its forces meant them no harm.

       “We give full assurance to the honorable people of Panjshir that they will not be discriminated against,” Mr. Mujahid said. “They are all our brothers, and we will serve a country and a common goal.”

       The Taliban took over the majority of Afghanistan with astonishing speed after the withdrawal of most American forces. The U.S.-trained Afghan security forces melted away before the militants, sometimes without firing a shot, culminating in the Taliban’s seizure on Aug. 15 of the capital, Kabul.

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       Fighters said to be in front of the provincial governor’s office in Panjshir Province in Afghanistan, in a photograph posted to social media on Monday. Credit...via Reuters

       Still, pockets of resistance remained, particularly in the north, where the Taliban have long clashed with other paramilitary groups. In late August, a group of former mujahedeen fighters and Afghan commandos said that they had begun a war of resistance in Panjshir. A rugged area about 70 miles north of Kabul, Panjshir, with its mountains and craggy valleys, has provided cover for insurgents since the Soviet occupation of the 1980s.

       The Taliban in recent days reported making gains against the resistance forces and killing some senior leaders, including the resistance spokesman, Fahim Dashti. Ahmad Zia Kechkenni, Mr. Dashti’s brother, said in an interview on Monday that the spokesman “was martyred for defending his people and country, Afghanistan.”