The Taliban seized more major cities on Friday as they raced towards full control of Afghanistan and inched closer to Kabul, with the United States preparing to airlift thousands of people a day out of the capital.

The first US Marines leading the evacuations landed at the civilian airport in Kabul, one of the few cities still in government hands after the Taliban took control of their spiritual heartland Kandahar, Afghanistan's second-largest city.

Map of Afghanistan locating the cities that have fallen to the Taliban in the past week, as of August 12
Map of Afghanistan locating the cities that have fallen to the Taliban in the past week, as of August 12 AFP / Paz PIZARRO

The scale and speed of the onslaught has shocked Afghans and the US-led alliance that poured billions into the country after toppling the Taliban in the wake of the September 11 attacks nearly 20 years ago.

Days before a final US withdrawal ordered by President Joe Biden, individual soldiers, units and even whole divisions have surrendered -- handing the insurgents even more vehicles and military hardware to fuel their lightning advance.

Pul-e-Alam, capital of Loghar province, was the latest city to fall Friday, putting the Taliban just 50 kilometres (30 miles) from Kabul.

Taliban fighters in Ghazni on Thursday after seizing the city, just 150kms from Kabul
Taliban fighters in Ghazni on Thursday after seizing the city, just 150kms from Kabul AFP / -

Khairddin Logari, a resident of the capital, summed up the confusion.

"We don't know what is going on," he told AFP.

Members of the Taliban patrol the Afghan city of Farah in the country's west. Taliban fighters have now taken more than a quarter of Afghanistan's provincial capitals in less than a week.
Members of the Taliban patrol the Afghan city of Farah in the country's west. Taliban fighters have now taken more than a quarter of Afghanistan's provincial capitals in less than a week. AFPTV / Najiba NOORI

British Defence Minister Ben Wallace said Friday that the hasty pullout, which London followed after Biden ordered the withdrawal of the larger US contingent, had been "a mistake".

Prime Minister Boris Johnson promised to "not turn our backs on Afghanistan" but acknowledged that outside powers had limited power to impose a solution.

The Taliban have engaged in a lightning offensive that has seen them seize the strategic city of Ghazni and 9 other provincial capitals in a week
The Taliban have engaged in a lightning offensive that has seen them seize the strategic city of Ghazni and 9 other provincial capitals in a week AFP / -

Earlier Friday, officials and residents in Kandahar told AFP that government forces had withdrawn en masse to a military facility outside the southern city.

Afghan security forces stand guard along the roadside in Herat, from where government forces pulled out on Thursday as Taliban advanced
Afghan security forces stand guard along the roadside in Herat, from where government forces pulled out on Thursday as Taliban advanced AFP / -

"Kandahar is completely conquered. The Mujahideen reached Martyrs' Square," a Taliban spokesman tweeted, referring to a city landmark.

Hours later, the Taliban said they had also taken control of Lashkar Gah, the capital of neighbouring Helmand province.

A security source confirmed the fall of the city, telling AFP that the Afghan military and government officials had evacuated Lashkar Gah after striking a local ceasefire deal with the militants.

The Taliban have taken control of Kandahar, the second biggest city in Afghanistan
The Taliban have taken control of Kandahar, the second biggest city in Afghanistan AFP / -

In Herat on Friday, the Taliban captured the city's long-time strongman Ismail Khan, who helped lead the defence of the provincial capital along with his militia fighters.

The warlord's spokesman later confirmed Khan had been allowed to return to his residence following negotiations with the insurgents.

Helicopters flitted back and forth between Kabul's airport and the sprawling US diplomatic compound in the heavily fortified green zone -- 46 years after choppers evacuated Americans from Saigon, signalling the end of the Vietnam War.

Biden ordered troops to the airport to start pulling out some 30,000 embassy employees as well as Afghans and their families who fear retribution for working as interpreters or in other support roles for the United States.

Pentagon spokesman John Kirby said that most of the 3,000 troops would be in place by Sunday and "will be able to move thousands per day" out of Afghanistan.

"Capacity is not going to be a problem," he told reporters.

He said Kabul was "not right now in an imminent threat environment" but that the Taliban appeared to be following a strategy of isolating the city to force a surrender.

Britain is also evacuating citizens and other nations including Denmark, Norway and Germany announced that their Kabul embassies would be temporarily shuttered or operations reduced due to security concerns.

The insurgents have taken over more than half the nation's provincial capitals in the past week and encircled the biggest city in the north, the traditional anti-Taliban bastion of Mazar-i-Sharif, which is now one of the few holdouts remaining.

In Kandahar, resident Abdul Nafi told AFP the city was calm after the government forces pulled out early Friday.

"I came out this morning, I saw Taliban white flags in most squares of the city," he said. "I thought it might be the first day of Eid."

UN Secretary-General Antonio Guterres renewed calls for a diplomatic solution and said he was "deeply disturbed" by accounts of poor treatment of women in areas seized by the Taliban, who imposed an ultra-austere brand of Islam on Afghanistan during their 1996-2001 rule.

"It is particularly horrifying and heartbreaking to see reports of the hard won rights of Afghan girls and women being ripped away," Guterres said.