A city in southwestern Afghanistan has become the first provincial capital to fall to the Taliban since the militants launched a sweeping offensive earlier this year.
Local officials said the Taliban had captured Zaranj, in Nimroz province, in a major blow to government forces.
The insurgents continue to make rapid advances across 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 the southern cities of Kandahar and Lashkar Gah.
The UN’s special envoy for Afghanistan, Deborah Lyons, on Friday said the war there had entered a “new, deadlier, and more destructive phase”, with more than 1,000 civilians killed in the past month.
She warned that the country was heading for “catastrophe”, and called on the UN Security Council to issue an “unambiguous statement that attacks against cities must stop now”.
Later on Friday, the UK government advised all its citizens in Afghanistan to leave because of the worsening security situation.
City ‘fell without a fight’
Taliban insurgents claimed victory in Zaranj – a major trading hub near the Iranian border – in a post shared on Twitter.
“This is the beginning, and see how other provinces fall in our hands very soon,” a Taliban commander told Reuters news agency.
Pictures posted on social media showed civilians looting items from government buildings. Taliban insurgents were photographed inside the local airport and posing at the entrance to the city.
The militants made a sustained bid to seize the city after capturing surrounding districts.
But Nimroz’s Deputy Governor Roh Gul Khairzad told reporters that Zaranj had fallen “without a fight”.
She and other local officials complained of a lack of reinforcements from the Afghan government.
“The city was under threat for a while, but no one from the central government listened to us,” Ms Khairzad said.
The last time the Taliban captured a provincial capital was in 2016, when they briefly held the northern city of Kunduz.
The militants launched a major military campaign in May, to coincide with the phased withdrawal of US and Nato forces after 20 years of military operations. The capture of Zaranj will add to their momentum, analysts say.
Overnight, US and Afghan forces launched air strikes on the group’s positions in Lashkar Gah, the capital of Helmand province.
Government troops have vowed not to lose the strategically significant city, and fighting there has been fierce. Officials have urged civilians to evacuate, with thousands trapped or fleeing for their lives.
In Herat, people have also been fleeing their homes in anticipation of a government offensive against Taliban positions.
“We have nothing left and we do not know where to go,” one resident told AFP news agency.
‘An affront to human rights’
Earlier on Friday, the director of Afghanistan’s government media centre was assassinated by Taliban militants in the capital, Kabul. Dawa Khan Menapal was shot dead as he left a mosque in his car.
The Taliban said he had been “punished for his deeds”.
Afghan government colleagues condemned the killing as shocking and cowardly.
US Chargé d’Affaires to Afghanistan Ross Wilson tweeted that he was “saddened and disgusted” by the killing, adding: “These murders are an affront to Afghans’ human rights and freedom of speech.”
Days earlier, an attack on the Afghan defence minister’s house in Kabul left at least eight people dead. The minister, Bismillah Khan Mohammadi, was not at home at the time.
At a UN Security Council meeting on Friday, representatives voiced concerns over the growing bloodshed.
Afghanistan’s envoy Ghulam Isaczai called on the Security Council to take action to pressure the militants to halt their attacks and take part in meaningful peace talks.
“It is our collective responsibility to stop them from destroying Afghanistan and threatening the world community,” he said.
Meanwhile, the chair of the Afghanistan Independent Human Rights Commission told the BBC that countries within the region in particular needed to tell the Taliban that coming to power through violence would mean that their government would not be recognised.