Last updated 9.06pm -

The Taliban gained control of the Afghan capital Kabul on Sunday with hardly a shot being fired as the Afghan president fled the country and the US shuttled its embassy staff out by helicopter.

Twenty years after the hardline Islamic group was forced out of Kabul by US-backed forces, it was back in control of the presidential palace and talks were being held with ministers over a peaceful takeover.

The Taliban's militants surrounded Kabul early on Sunday following an astonishing rout of government forces and warlord militias achieved in just 10 days as thousands of government troops surrendered or vanished. 

Afghan President Ashraf Ghani said that he had fled the country to "prevent a flood of bloodshed", as the Taliban entered the capital.

Ghani, who did not say where he had gone, said he believed "countless patriots would be martyred and the city of Kabul would be destroyed" if he had stayed behind.

"The Taliban have won... and are now responsible for the honour, property and self-preservation of their countrymen," he said in a statement posted to Facebook.

The Taliban's takeover triggered fear and panic in Kabul among residents fearful of the group's hardline brand of Islam.

"I saw police taking off their uniforms and putting on shalwar kameez," said one resident, referring to traditional South Asian clothing.

- Isolated -

The scale and speed of the insurgents' advance have shocked Afghans and the US-led alliance that poured billions into the country over the past two decades.

President Ashraf Ghani's government was left completely isolated after the Taliban claimed the anti-Taliban northern stronghold of Mazar-i-Sharif and the eastern city of Jalalabad on Saturday.

Like with most of the other captured cities, the seizure of power came after government forces surrendered or retreated.

It left the Taliban holding all the cards in any negotiated surrender of the capital.

On Saturday Ghani sought to project authority with a national address in which he spoke of "re-mobilising" the military while seeking a "political solution" to the crisis.

He offered no public comments on Sunday.

- Evacuations -

President Joe Biden ordered the deployment of an additional 1,000 US troops to help secure the emergency evacuation from Kabul of embassy employees and thousands of Afghans who worked for American forces and now fear Taliban reprisals.

That was on top of the 3,000 American soldiers deployed in recent days, and 1,000 left in-country after Biden announced in May that the final withdrawal of the 20-year military presence in Afghanistan would be completed by September 11.

That decision has come under increased scrutiny given the collapse of the Afghan armed forces, but he insisted Saturday there was no choice.

"I was the fourth president to preside over an American troop presence in Afghanistan -- two Republicans, two Democrats. I would not, and will not, pass this war onto a fifth," Biden said.

Helicopters on Sunday were shuttling between the US embassy and the airport, recalling memories of the evacuation of the last US staff from Vietnam we Saigon fell in 1975.

US Secretary of State Antony Blinken rejected comparisons with the chaotic American departure from Saigon.

"This is not Saigon," he told ABC. "The fact of the matter is this: We went to Afghanistan 20 years ago with one mission in mind. That was to deal with the people that attacked us on 9/11. That mission has been successful."

Videos posted on pro-Taliban social media accounts showed the group's heavily armed fighters in cities across the country, waving white flags and greeting locals. 

Most of the fighters appeared young, suggesting they were most likely infants or unborn when the Taliban was toppled from power in 2001.

In Mazar-i-Sharif, Taliban fighters quickly took charge on Sunday.

"They are parading on their vehicles and motorbikes, firing into the air in celebration," said Atiqullah Ghayor, who lives near the city's famed blue mosque.

Warlords Abdul Rashid Dostum and Atta Mohammad Noor, who had led a militia resistance in the city to support government forces, had fled to Uzbekistan, about 30 kilometres to the north, an aide to Noor said.

- Panic -

As the Taliban closed in on the capital, panicked residents swarmed banks for a second straight day, hoping to withdraw their savings. 

Many were already resigned to the Taliban taking power.

"My only wish is that their return leads to peace. That is all we want," said Kabul shopkeeper Tariq Nezami.

For the tens of thousands who have sought refuge in Kabul in recent weeks, the overwhelming mood was one of apprehension and fear.

One doctor who arrived in the capital with his 35-strong family from Kunduz said he planned to return today.

"I am worried there will be a lot of fighting here. I would rather return home, where I know it has stopped," he told AFP, asking not to be named.