An Afghan footballer who played for the national youth team fell to his death after trying to cling to a US plane airlifting people out of Taliban-controlled Kabul, a sports federation said Thursday.

The General Directorate of Physical Education and Sports of Afghanistan, a government institution that worked with sporting groups, confirmed the death of Zaki Anwari in the mayhem that erupted at the airport in the capital this week.

"Anwari, like thousands of Afghan youths, wanted to leave the country but fell off a US plane and died," the group said in a statement posted on Facebook.

Thousands of Afghans have flocked to the airport this week in a bid to flee the country, following the Taliban's lightning offensive that ended with them assuming power when president Ashraf Ghani fled.

In a harrowing video from the airport on Monday, hundreds of people were seen running alongside a US Air Force plane as it gathered speed on the runway -- several men desperately holding onto the side.

Further clips on social media appeared to show two people falling to their deaths from a C-17 aircraft after it took off.

Human remains were later found in a wheel well, the US military confirmed, adding that it was investigating the reported deaths linked to the C-17.

"Before the air crew could offload the cargo, the aircraft was surrounded by hundreds of Afghan civilians," US Air Force spokeswoman Ann Stefanek said.

"Faced with a rapidly deteriorating security situation around the aircraft, the C-17 crew decided to depart the airfield as quickly as possible."

US President Joe Biden has come under pressure at home and abroad to explain how his administration was seemingly unprepared for the Taliban's quick assault -- and the way in which US troops are retreating from Afghanistan.

Memories of the Taliban's brutal regime of the 1990s -- which saw music and television banned, people stoned to death and women confined to their homes -- have caused panic about what lies ahead, prompting many Afghans to try to flee.