A city in southwestern Afghanistan has become the country’s first provincial capital to fall to the Taliban in recent years, officials told the BBC.

Local sources said the insurgents had captured Zaranj, in Nimroz province, on Friday afternoon, in what would be a major blow to government forces.

It comes as the insurgents continue to make rapid advances in the country, as foreign troops withdraw.

They have taken swathes of countryside and are now targeting key cities.

Other provincial capitals under pressure include Herat in the west and Lashkar Gah in the south.

Zaranj is a major trading hub near the border with Iran. After capturing surrounding districts, the militants had been making a sustained attempt to capture the city.

Two official sources told the BBC that the city had been taken. One said fighting was still happening around the National Directorate of Security office.

An unnamed spokesperson for Nimroz’s police told Reuters news agency that the Taliban had been able to capture the city because of a lack of reinforcements from the government.

The Taliban claimed victory in a post shared on Twitter.

“This is the beginning and see how other provinces fall in our hands very soon,” a commander for the group told Reuters.

Some reports said a deal had been reached with the Taliban, allowing officials to flee to Iran with their families.

The government has not yet officially commented on the city’s reported fall.

Pictures posted on social media showed civilians looting items from government buildings.

The capture of Zaranj would add to the momentum of the Taliban, who have been launching a major offensive across the country in recent months as US forces withdraw after 20 years of military operations.

Earlier on Friday, the director of Afghanistan’s media and information centre was assassinated by Taliban militants in the capital, Kabul. The Taliban said Dawa Khan Menapal had been “punished for his deeds”.