Look: Over 600 Afghans cram into US cargo plane in desperate flight from Kabul

Kabul - According to Boeing, the aircraft in question can carry 134 passengers.

More than 600 Afghan men, women and children, crouching and crammed up against each other on the floor of a US military plane, left Kabul after the city was seized by Taliban insurgents.

A photograph showing the Afghan civilians — some clutching luggage, others bottle-feeding infants — on the C-17 cargo aircraft has gone viral on social media.

A US official told Reuters about 640 people clambered onto the flight from Kabul on Sunday, when thousands of people desperate to flee the country surged to the airport in the Afghan capital.

"The unusually high number of passengers was the result of a dynamic security environment that necessitated quick decision making by the crew which ultimately ensured these passengers were quickly taken outside the country," the official said.

According to the manufacturer, Boeing, the C-17 Globemaster III can carry 134 passengers, including 54 on side seats and 80 on pallets on the floor.

Many of the Afghans climbed aboard the plane via a half-open ramp, before the flight left for Qatar with one of the highest number of passengers ever flown on such an aircraft, US defence and security news site Defense One reported. Reuters could not immediately verify those details.

Other distressing videos and photos have emerged from Kabul airport, where witnesses say several people have died, and show people clambering up overhead gangways and clinging to the landing gear of taxiing planes in desperate attempts to flee.

"We need many more such planes," said Kenneth Roth, executive director of non-governmental organisation Human Rights Watch.