Hollywood star Angelina Jolie has joined Instagram and said she will use the platform to share voices fighting for their basic human rights, including those coming out of Afghanistan after the country's takeover by the Taliban.

In her first post on the social media platform, Jolie shared a letter she said she received from an anonymous teenage girl in Afghanistan, who feared living in the country under the current circumstances.

"Right now, the people of Afghanistan are losing their ability to communicate on social media and to express themselves freely.

"So I've come on Instagram to share their stories and the voices of those across the globe who are fighting for their basic human rights," the 46-year-old Oscar-winning actor wrote.

The Taliban swept into Kabul on Sunday after President Ashraf Ghani fled the country, bringing a stunning end to a two-decade campaign in which the US and its allies had tried to transform Afghanistan.

It has sparked chaos at Kabul's airport, from where America and allied nations are trying to safely evacuate thousands of their citizens and allies.

Jolie recalled the time when she was on the border of Afghanistan two weeks before the September 11, 2001 terror attacks in New York and said that she met Afghan refugees who had fled the Taliban nearly 20 years ago.

"It is sickening to watch Afghans being displaced yet again out of the fear and uncertainty that has gripped their country. To spend so much time and money, to have bloodshed and lives lost only to come to this, is a failure almost impossible to understand," she wrote.

What is also sickening is how the Afghanistan refugees are being "treated like a burden", Jolie said in an apparent criticism of world leaders.

"Knowing that if they had the tools and respect, how much they would do for themselves. And meeting so many women and girls who not only wanted an education, but fought for it.

"Like others who are committed, I will not turn away. I will continue to look for ways to help. And I hope you'll join me," the actor concluded her post.

Jolie posted the entire letter of the young girl along with a photo of seven Afghan women standing with their backs to the camera.

In the letter, the girl detailed her difficulties of going to school after the Taliban's takeover.

"We all had rights, we (were) able to defend our rights freely, but when they came, we are all afraid of them, and we think all our dreams are gone," the girl wrote.

Since her debut, Jolie's first post has received over 1.3 million likes on Instagram. She has also amassed 4.2 million followers on the social media platform.