Afghans were bracing themselves for life under strict Islamic rule on Monday after the Taliban drove the US-backed government of Ashraf Ghani from power to establish control of Kabul.

Thousands of residents filled the airport and throngs of people tried to push their way on to planes in a desperate effort to flee after the Islamic fighters marched into the capital on Sunday.

The Taliban’s capture of Kabul followed a sweeping offensive that saw the Islamic group overrun most of the country, facing little armed resistance as it encircled the capital.

Analysts said that many Afghan troops had calculated that the fall of the unpopular government was inevitable and opted to surrender peacefully rather than die for an unpopular cause.

Ghani, a former World Bank official, had resisted pressure to resign and initiate a power-sharing arrangement with the Taliban. He fled the country to an undisclosed location as an assault on the capital appeared imminent.

Taliban fighters took control of the empty presidential palace and abandoned police posts in the capital without a struggle on Sunday.

The US and other western governments urged the Taliban to “respect and facilitate the safe and orderly departure of foreign nationals who wish to leave”.

Ben Wallace, the UK defence secretary, said on Monday that the Taliban was in control of the country. “I have engaged through a third country yesterday to make sure we seek assurances from the Taliban to protect our people and indeed the people we’re trying to work to get out,” he told Sky News.

The US has almost 6,000 troops in Kabul but military officials said their priority was to facilitate the safe and rapid evacuation of US civilians, other foreign nationals and some Afghan allies.

Ned Price, US state department spokesperson, said all embassy personnel had been moved out of Kabul and were congregated at the airport, where a de facto embassy had been established.

The Taliban ruled Afghanistan from 1996 to 2001 and enforced a strict interpretation of Islamic law, carrying out public executions, stoning women accused of adultery and cutting off the hands of accused thieves. The group was ousted by a US-led invasion following the terror attacks of September 11 2001.

The Taliban has sought to publicly reassure Afghans that it had moderated its approach in the two decades since. Mullah Baradar, a senior Taliban leader, urged his fighters to show “humility” following the group’s virtually bloodless seizure of power.

“We reached a victory that wasn’t expected,” he said in a video message from Qatar, where he has been negotiating with Afghan political leaders and foreign government officials. “We should show humility in front of Allah. Now, it’s about how we serve and secure our people and ensure their future and good life to the best of our ability.”

Baradar added that the Taliban was in discussions with other Afghan leaders over the formation of “an open, inclusive Islamic government”.

But many Afghans — particularly educated women — remained intensely anxious. The Taliban has reportedly freed thousands of inmates from Kabul’s main prison, many of whom are Islamist fighters associated with militant groups.

“The fear just sits inside your chest like a black bird. It opens its wings and you can’t breathe,” Muska Dastageer, a political-science professor at the American University of Afghanistan, wrote on Twitter early on Monday morning.

President Joe Biden warned the Taliban over the weekend that any action that threatened Americans would be met with “a swift and strong military response”.

US forces deployed to the country were focused on securing the airport, but officials remained concerned about a potential Taliban attack.

“[The Taliban] see those forces as invaders so they are likely to try to attack them,” Mike Morell, the former acting CIA director, told CBS news channel. 

But Morell warned that US troops could also be at risk from disgruntled Afghan security personnel, who felt betrayed by the abrupt American withdrawal.

“There are many Afghan security forces that are immensely angry at what the US has done here, and they could take out their weapons and shoot the Americans that they’re working with,” he said.

Many Afghans have raged at the US and other western governments for abandoning them to the Taliban. “My brain, my heart and soul died today,” Sara Wahedi, a former Afghan official wrote on Twitter. “I will get up and keep working — I know that. But we will never be the same, never.”