The Taliban have captured Herat – Afghanistan’s third-largest city and a strategic provincial capital near Kabul.
The seizure marks the biggest prize yet for the Taliban. The group now has taken 11 of Afghanistan’s 34 provincial capitals.
Earlier, the insurgents had taken another provincial capital, Ghazni, just 80 miles from Kabul, posting videos of themselves on the city’s streets unopposed.
Afghan officials told the Associated Press news agency Taliban fighters were raising their flags and the city had calmed after hours of heavy fighting.
US intelligence has warned that Kabul could fall within the next 90 days, and the US Embassy there is urging American citizens to leave the country immediately.
The latest advances come as intense fighting has broken out on the streets of Kandahar, Afghanistan’s second largest city, which is situated 480km (300 miles) south-west of the capital.
Civilians are fleeing violence there as the Taliban threatens to take control of the region.
The battle for control of Lashkar Gah, west of Kandahar in Helmand Province, continues too – where the Taliban have captured a police headquarters.
Access roads to Kabul through nearby valleys were packed with civilians trying to get into the city amid the rapid gains made by the Taliban, but there are fears that suicide bombers and insurgents could be among them.
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On Wednesday, David Miliband, president of the International Rescue Committee, warned the West not to take its eyes off Afghanistan as the Taliban’s forces continue to make gains after British and US troops were withdrawn.
Mr Miliband said 5,000 civilians were killed in the most recent fighting, 30,000 people a week are fleeing the country, and 350,000 people are homeless.
He added the refugee danger is “real and present” to neighbouring states, with 100,000 leaving Afghanistan each month and going into Pakistan and Iran.