By Mirwais Harooni and Jessica Donati
KABUL (Reuters) - Taliban militants have captured a large police base in northeast Afghanistan, forcing the mass surrender of more than a hundred policemen and pushing closer to a strategic pass at the border with Pakistan, local officials and security sources said on Sunday.
The Taliban captured food, weapons and ammunition from the Tirgaran base in the northeastern province of Badakhshan, which borders China, Pakistan and Tajikistan.
"The enemy got weapons and ammunition from police forces at the Tirgaran base that will allow them to fight for a long time," provincial governor Shah Waliullah Adib told Reuters, adding that the captured forces had later been released.
"We will launch an operation soon and take back control of the base."
The capture of the base on Saturday after days of fighting was perhaps the Taliban's greatest advance in Badakhshan since being ousted from power in 2001, according to a Western security report.
It said the Taliban gains cut off the route to China and left just one significant government outpost before a strategically important crossing at the Pakistani border.
"If successful, they [Taliban] will be able to establish a corridor... facilitating the cross-border movement of fighters currently based in Pakistan," the report said.
The Taliban said in a statement that local elders had negotiated the release of 120 captured policemen, and that it had obtained guarantees they would not return to battle.
Afghan forces are fighting the resurgent Taliban with only limited coalition support, after most foreign troops withdrew from Afghanistan in 2014 when NATO combat operations ended.
The hardline Islamist insurgents have reorganized since being ousted from power by a U.S.-led coalition in 2001, gaining territory in rural areas and briefly threatening a major city in the north in this year's spring offensive.
A Western organization that tracks security incidents recently reported that opposition group activity hit an "unprecedented" level in the first six months of 2015.
It recorded more than 9,600 incidents involving armed opposition groups. Afghan civilians are often caught in the crossfire and violence has also taken a heavy toll on the population.
In 2014, over 10,000 people were killed or wounded, according to the United Nations.
(Editing by Ros Russell)