Passengers were left fighting for their lives on a flight to Bangkok as the passengers experienced such severe turbulence that some lost consciousness and suffered from internal bleeding.

The Aeroflot flight from Moscow left three babies with broken spines after the infants were thrown out of their mothers' arms in the shock turbulence, one hour before landing in the Thai city.

People in the aisles of the aircraft were said to be the most seriously injured.

Twenty-five injured people were treated in hospital after the incident on the Boeing 777 aircraft, with two undergoing immediate urgent surgery.

Passenger Evgenia Zibrova was so horrified by the event that she filmed the catastrophe, and posted the video online.

"Numerous air pockets one hour before landing led to broken bones, internal and external bleeding," said Zibrova in a comment online.

"Lots of people from the tail cabin have broken their noses, several people have probably broken their spines.

"Babies are covered in bruises, people lost consciousness. Thanks that we are still alive. Aeroflot, please help these people."

The shocking footage also shows items from food and drinks trolleys strewn across the aisles.

Vladimir Sosnov, deputy head of Russian Consulate in Thailand, said: "The injured suffered multiple fractures. There are both Russian and foreign citizens among them."

He said: "Apparently, those who were injured did not have their seat belts fastened."

A source told news agency Interfax: "A Boeing 777 plane suddenly got into the zone of strong turbulence before starting to descend.

"There had been no order to fasten seat belts at that moment.

"As a result, the plane was jolted by hundreds of metres, and some passengers were thrown into the space between the chairs suffering traumas."

An airport source told TASS that 25 people were injured when flight SU-270 flew into "a zone of strong turbulence" while approaching the Thai capital.

"Nineteen people were hospitalised. Other passengers received the necessary aid and refused from [sic] further treatment," the source said.

Turbulence is a normal event during flights. It is caused when normal smooth air flow that plans travel through is disturbed. It can be caused by warm air rising through an area of cold air; a natural or man-made structure changing airflow; or where neighbouring pockets of air are flowing in different directions.

Turbulence is difficult to predict and so can strike suddenly.

The US Federal Aviation Administration says that around 58 people in the US are injured by turbulence each year, and during 1980-2008, there were three people were killed during turbulence – two of those fatalities occurred when the passengers were not wearing seatbelts, despite being told to.