Flag-waving protesters took to the streets of several Afghan cities on Thursday as popular opposition to the Taliban spread, and a witness said several people were killed when the militants fired on a crowd.

"Our flag, our identity," a crowd of men and some women waving black, red and green national flags shouted in the capital, a video clip posted on social media showed, on the day Afghanistan celebrates its 1919 independence from British control.

One woman walked with a flag wrapped around her shoulders. Some of those marching also chanted "God is greatest".

A Taliban spokesman was not immediately available for comment.

The Taliban have presented a moderate face to the world since they marched into Kabul on Sunday, saying they want peace, will not take revenge against old enemies and will respect the rights of women within the framework of Islamic law.

How the Taliban handle the protests, which have included people tearing down white Taliban flags, according to media, could determine whether people put faith in their assurances that they have changed since their 1996-2001 rule, when they severely restricted women, staged public executions and blew up ancient Buddhist statues.

In Asadabad, capital of the eastern province of Kunar, several people were killed during a rally but it was not clear if the casualties resulted from Taliban firing or from a stampede that it triggered, witness Mohammed Salim said.

"Hundreds of people came out on the streets," Salim said. "At first I was scared and didn't want to go but when I saw one of my neighbours joined in, I took out the flag I have at home.

"Several people were killed and injured in the stampede and firing by the Taliban."

Protesters also took to the streets of the city of Jalalabad and a district of Paktia province, both also in the east.

On Wednesday, Taliban fighters fired at protesters waving flags in Jalalabad, killing three, witnesses and media reported. Media reported similar scenes in Asadabad and another eastern city, Khost, on Wednesday.

First Vice President Amrullah Saleh, who is trying to rally opposition to the Taliban, expressed support for the protests.

"Salute those who carry the national flag and thus stand for dignity of the nation," he said on Twitter.

Saleh said on Tuesday he was in Afghanistan and the "legitimate caretaker president" after President Ashraf Ghani fled as the Taliban took Kabul on Sunday.

People carry Afghan flags as they take part in an anti-Taliban protest in Jalalabad, Afghanistan August 18, 2021 in this screen grab taken from a video. Pajhwok Afghan News/Handout via REUTERS

CALL FOR END TO AIRPORT CROWDS

In an op-ed for the Washington Post, Amad Massoud, leader of the National Resistance Front of Afghanistan, based in the old anti-Taliban stronghold of the Panjshir Valley, northeast of Kabul, called for Western support to fight the Taliban.

"I write from the Panjshir Valley today, ready to follow in my father’s footsteps, with mujahideen fighters who are prepared to once again take on the Taliban," wrote Massoud, the son of Amhad Shah Massoud, a veteran guerrilla leader assassinated by suspected al Qaeda militants on behalf of the Taliban in 2001.

Other former Afghan leaders including ex-president Hamid Karzai, have been holding talks with the Taliban as they put together a new government.

While Kabul has been generally calm since Taliban forces entered on Sunday, the airport has been in chaos as people rushed for a way out of the country.

Twelve people have been killed in and around the airport since then, a NATO and a Taliban official said. The deaths were caused either by gun shots or by stampedes, the Taliban official said.

He urged people who do not have the legal right to travel to go home. "We don't want to hurt anyone at the airport," said the Taliban official, who declined to be identified.

On Wednesday, witnesses said Taliban gunmen prevented people from getting into the airport compound. A Taliban official said soldiers had fired into the air to disperse the crowd.

Gunmen unleashed sustained fire into the air on Thursday at several entrances to the airport, sending the crowds, including women clutching babies, scattering. It was not clear if the men firing were Taliban or security staff helping U.S. forces inside.

The United States and other Western powers pressed on with the evacuation of their nationals and some of their Afghan staff from the capital's airport, from where about 8,000 people have been flown out since Sunday, a Western security official said.

Under a pact negotiated last year by former President Donald Trump's administration, the United States agreed to withdraw its forces in exchange for a Taliban guarantee they would not let Afghanistan be used to launch terrorist attacks.

The Taliban also agreed not to attack foreign forces as they left.

U.S. President Joe Biden said U.S. forces would remain until the evacuation of Americans was finished, even if that meant staying past an Aug. 31 U.S. deadline for withdrawal.