Taliban fighters have entered the outskirts of the Afghan capital Kabul and said they are awaiting a “peaceful transfer” of the city after promising not to take it by force.

But amid the uncertainty, panicked workers fled government offices and helicopters landed at the US embassy in Kabul.

Three Afghan officials told the Associated Press that the Taliban were in the districts of Kalakan, Qarabagh and Paghman in the capital.

In a nationwide offensive that has taken just over a week, the Taliban have defeated, co-opted or sent Afghan security forces fleeing from wide swathes of the country, even though they had some air support from the US military.

The lightning speed of the Taliban offensive has shocked many and raised questions about why Afghan forces crumbled despite years of US training and billions of dollars spent.

Just days ago, an American military assessment estimated it would be a month before the capital would come under insurgent pressure.

Taliban spokesman Suhail Shaheen told Qatar’s Al-Jazeera English satellite news channel that the insurgents are “awaiting a peaceful transfer of Kabul city”.

He declined to offer specifics on any possible negotiations between his forces and the government.

But when pressed on what kind of agreement the Taliban wanted, Shaheen acknowledged that they were seeking an unconditional surrender by the central government.

Taliban negotiators headed to the presidential palace on Sunday to discuss the transfer, said an Afghan official.

It remained unclear when that transfer would take place.

Anti-missile decoy flares are deployed as US Black Hawk military helicopters fly over the city of Kabul, Afghanistan
Anti-missile decoy flares are deployed as US Black Hawk military helicopters fly over the city of Kabul, Afghanistan (Rahmat Gul/AP)

The negotiators on the government side included former president Hamid Karzai and Abdullah Abdullah, the head of the Afghan National Reconciliation Council, an official said.

Mr Abdullah has been a longstanding vocal critic of President Ashraf Ghani, who long refused giving up power to get a deal with the Taliban.

The official, who spoke on condition of anonymity to discuss details of the closed-doors negotiations, described them as “tense”.

Acting defence minister Bismillah Khan sought to reassure the public in a video message.

“Authority has been given to a delegation that will be going to Doha (Qatar) tomorrow to reach an agreement on Afghanistan,” he said.

“I assure you about the security of Kabul.”

Earlier, the insurgents also tried to calm residents of the capital.

A US Chinook helicopter flies over the US embassy in Kabul, Afghanistan
A US Chinook helicopter flies over the US embassy in Kabul, Afghanistan (Rahmat Gul/AP)

“No-one’s life, property and dignity will be harmed and the lives of the citizens of Kabul will not be at risk,” the insurgents said in a statement.

However, a voice message circulating social media purportedly from a Taliban commander also warned “no-one is allowed to enter into Kabul province”.

Despite the pledges, panic set in as many rushed to leave the country through Kabul’s airport, the last route out of the country as the Taliban now hold every border crossing.

Rapid shuttle flights of Boeing CH-47 Chinook helicopters near the embassy began a few hours later after the militants seized the nearby city of Jalalabad.

Diplomatic armoured SUVs could be seen leaving the area around the post.

The US State Department did not immediately respond to questions about the movements.

However, wisps of smoke could be seen near the embassy’s roof as diplomats urgently destroyed sensitive documents, according to two American military officials.

The US embassy buildings in Kabul, Afghanistan
The US embassy buildings in Kabul, Afghanistan (Rahmat Gul/AP)

Sikorsky UH-60 Black Hawk helicopters, which typically carry armed troops, later landed near the embassy as well.

The US decided a few days ago to send in 3,000 fresh troops to help evacuate some personnel from the US embassy.

At Kabul International Airport, Afghan forces abandoned the field to Western militaries, said a pilot.

An Afghan flight earlier landed at the airport from Kandahar loaded with troops who surrendered to the Taliban, even after taking shrapnel damage from a mortar attack, the pilot said.

President Ashraf Ghani, who spoke to the nation on Saturday for the first time since the offensive began, appears increasingly isolated as well.

Warlords he negotiated with just days earlier have surrendered to the Taliban or fled, leaving Mr Ghani without a military option.

Ongoing negotiations in Qatar, the site of a Taliban office, have also failed to stop the insurgents’ advance.

Thousands of civilians now live in parks and open spaces in Kabul itself, fearing the future.

A man sells Taliban flags in Herat province, west of Kabul, Afghanistan
A man sells Taliban flags in Herat province, west of Kabul (Hamed Sarfarazi/AP)

Some ATMs stopped distributing cash as hundreds gathered in front of private banks, trying to withdraw their life savings.

Gunfire erupted at several points, though the Afghan presidency sought to downplay the shooting.

“The defence and security forces along with the international forces (are) working for the security of Kabul city and the situation is under control,” the presidency said amid the chaos.

Jalalabad, Afghanistan’s last major city besides the capital not held by the militants, fell to the Taliban earlier on Sunday.

Militants posted photos online showing them in the governor’s office in Jalalabad, the capital of Nangarhar province.

Abrarullah Murad, a legislator from the province, told the Associated Press that the insurgents seized Jalalabad after elders negotiated the fall of the government there.

Taliban fighters sit on the back of a vehicle in the city of Herat, west of Kabul, Afghanistan
Taliban fighters sit on the back of a vehicle in the city of Herat (Hamed Sarfarazi/AP)

Mr Murad said there was no fighting as the city surrendered.

The militants also took Maidan Shar, the capital of Maidan Wardak, on Sunday, only 55 miles from Kabul, Afghan legislator Hamida Akbari and the Taliban said.

Another provincial capital in Khost fell later on Sunday to the Taliban, said a provincial council member.

The fall on Saturday of Mazar-e-Sharif, the country’s fourth largest city, which Afghan forces and two powerful former warlords had pledged to defend, handed the insurgents control over all of northern Afghanistan.

Atta Mohammad Noor and Abdul Rashid Dostum, two of the warlords Mr Ghani tried to rally to his side days earlier, fled over the border into Uzbekistan on Saturday, said officials close to Dostum.

Writing on Twitter, Noor alleged a “conspiracy” aided the fall of the north to the Taliban, without elaborating.

“Despite our firm resistance, sadly, all the government and the Afghan security forces equipment were handed over to the Taliban as a result of a big organised and cowardly plot,” Noor wrote.

“They had orchestrated the plot to trap Marshal Dostum and myself too, but they didn’t succeed.”

Passengers walk to the departures terminal of Hamid Karzai International Airport in Kabul
Passengers walk to the departures terminal of Hamid Karzai International Airport in Kabul (Rahmat Gul/AP)

In his speech on Saturday, Mr Ghani vowed not to give up the “achievements” of the 20 years since the US-led invasion toppled the Taliban after the 9/11 attacks.

The US has continued holding peace talks between the government and the Taliban in Qatar this week, and the international community has warned that a Taliban government brought about by force would be shunned.

But the insurgents appear to have little interest in making concessions as they rack up victories on the battlefield.

“We have started consultations, inside the government with elders and political leaders, representatives of different levels of the community as well as our international allies,” Mr Ghani said.

“Soon the results will be shared with you,” he added, without elaborating further.

Many Afghans fear a return to the Taliban’s oppressive rule.

The group had previously governed Afghanistan under a harsh version of Islamic law in which women were forbidden to work or attend school, and could not leave their homes without a male relative accompanying them.

Salima Mazari, one of the few female district governors in the country, expressed fears about a Taliban takeover on Saturday in an interview from Mazar-e-Sharif, before it fell.

A passenger walks to the departures terminal of Hamid Karzai International Airport in Kabul, Afghanistan
A passenger heads to the departures terminal of Hamid Karzai International Airport (Rahmat Gul/AP)

“There will be no place for women,” said Ms Mazari, who governs a district of 36,000 people near the northern city.

“In the provinces controlled by the Taliban, no women exist there anymore, not even in the cities. They are all imprisoned in their homes.”

In a statement late on Saturday, however, the Taliban insisted their fighters would not enter people’s homes or interfere with businesses.

They also said they would offer an “amnesty” to those who worked with the Afghan government or foreign forces.

“The Islamic Emirate once again assures all its citizens that it will, as always, protect their life, property and honour and create a peaceful and secure environment for its beloved nation,” the militants said.

“In this regard, no-one should worry about their life.”

Despite the pledge, those who can afford a ticket have been flocking to Kabul International Airport, the only way out of the country as the Taliban took the last border crossing still held by the government on Sunday at Torkham.

Pakistan’s interior minister Sheikh Rashid Ahmed told local broadcaster Geo TV that Pakistan halted cross-border traffic there after the militants seized it.