“I can confirm the city of Zaranj, provincial capital of Nimroz, has fallen to the Taliban,” Roh Gul Khairzad, the deputy governor, told AFP.

She said the city – in southwest Afghanistan near the Iranian border – had fallen “without a fight”, and social media showed clips of insurgents roaming the streets, being cheered by local residents.

The veracity of the video could not immediately be confirmed.

While not strategically important, the fall of Zaranj is a psychological blow to the government, which is desperately defending a string of provincial capitals against a Taliban onslaught.

“The city was under threat for a while, but no one from the central government listened to us,” Khairzad said.

In a tweet, the Taliban earlier said their forces had captured strategic buildings including the administrative and police headquarters.

Fighting in Afghanistan’s long-running conflict has intensified since May, when foreign forces began the final stage of a withdrawal due to be completed later this month.