Image copyright Twitter: Tyler Bridges Image caption The incident angered many social media users, who described it as 'barbaric'

Outrage has erupted on Chinese and Vietnamese social media over the removal of a passenger from an overbooked United Airlines flight.

Videos posted online showed security officers dragging the man, who appears to be Asian, from the flight.

The man has not yet been identified. One eyewitness said he was a "Chinese American doctor", while another said he was originally from Vietnam.

United Airlines apologised for "having to re-accommodate" the passengers.

A video taken by Audra Bridges, who was on board the flight from Chicago to Louisville, shows the visibly distressed man being hauled out of his seat. The video has been shared millions of times and photos of his bloodied face also spread quickly.

Reports said the flight was overbooked and so passengers were randomly selected by United Airlines and asked to leave the plane.

According to the New York Times, passenger Tyler Bridges said that the man had shouted: "I'm being selected because I'm Chinese".

However a passenger who sat next to him told BBC Radio 5 Live that he said he was originally from Vietnam and had been living in Louisville, Kentucky, for about 20 years.

Ms Bridges in her post said: "This man is a doctor and [said he had] to be at the hospital in the morning. He did not want to get off." She added that everyone on board was "shaky and so disgusted".

Outraged passengers witnessing the unfolding events could also be heard in the background yelling and voicing their disgust.

Media playback is unsupported on your device Media caption Passenger dragged off a United flight. Video: Audra D. Bridges

Outrage over the controversial incident soon spread to the Chinese internet, where thousands of shocked and angry netizens took to China's top micro-blogging site Sina Weibo to express their anger with the US airline.

The story tagged "United Airlines forcibly removes passenger from airplane" also shot to the top of the site's trending charts, and was read more than 95.5m times.

"I understand that the airline's reason was that it oversold seats. So they were open to taking people's money easily and bullying someone, who really needed to be somewhere, when it was of no fault of his own?" wrote Weibo user madanamada in a lengthy blog post that drew more than 550 likes from netizens.

"Look at the way they manhandled the poor Chinese man. He doesn't look young either. It must have been downright humiliating to have been dragged off in full view of everyone, kicking and screaming."

Another user said: "Active racial profiling clearly took place here. And America wonders why people attack it for not having respect for social movements?"

Image copyright Sina Weibo

Other users like Chang Xiao from Shanghai, shared personal "horror stories" of flying with United Airlines.

"When I was studying overseas, I flew with this airline and found their flight attendants were horribly rude and impatient. My friend and I thought it was because we were Chinese and this incident proves our feelings were correct. How horrible of them to throw a passenger off board just because he looked Asian. What is happening with the world today?"

Over on Chinese chat app WeChat, users called for a boycott of the airline until official action was taken. But some users pointed out that the issue was not necessarily about race.

"The United Airlines should pay a price for this. Not only because the person who was removed from the flight is of Chinese descent, anyone should have the right to refuse such unreasonable treatment. This is dignity," said on user.

In Vietnam, social media users echoed the Chinese anger.

"You cannot beat someone up then just say I'm sorry," wrote Yeu La Phai Thuong on Dai Ky Nguyen website. "The man is old so the airlines don't appear at all human. They are also so greedy."

"Incidents happen everywhere, let's hope that the airline comes up with a fair solution and compensates the man," wrote Mai on Tuoi Tre forum.

Another commentator, Thanh, asked wryly: "Oh, is this what they call American civilisation??"

Reporting by the BBC's Heather Chen and Grace Tsoi.