Enraged Chinese netizens are calling for a boycott of US carrier United Airlines after footage of an Asian passenger being dragged off an "overbooked" flight went viral online.

A Sina Weibo microblogging website tag "United Airlines forcibly bumps a passenger" was viewed over 150 million times and garnered more than 90,000 comments, making it the top trending topic of the day on the platform, reported Global Times daily on Tuesday. 

The elderly doctor was manhandled after he refused to give up his seat on the flight before it departed from Chicago O'Hare International Airport on its journey to Louisville, Kentucky, on Sunday. 

Videos posted online showed police dragging him from his seat, injuring his face, throwing him on the floor and dragging him along the aisle by his arms, while his glasses slid down his face and his shirt rode up his chest.

The doctor, who had identified himself as Chinese according to passenger accounts in the media, returned to the aircraft with his face bleeding. He collapsed and was taken away on a stretcher, according to a passenger.

The incident sparked outrage on the Chinese Internet with many Net users condemning the airline for being brutal or even accusing it of being racist. 

"The company may think that Asian Americans are always obedient but this incident has crossed the line too much," a Weibo user commented.

"Although it is legal to sell more tickets than there are seats on the plane, violently forcing a passenger to leave the plane regardless of his dignity and rights is horrible. Is this the way United Airlines boasts the spirit of contract and human rights?" another user wrote. 

A Chinese aviation industry insider told the Global Times on Tuesday that it was routine for airlines to oversell flights to avoid empty seats and compensation is often offered to passengers who voluntarily give up their place on the plane.

The outrage over the incident was not reduced by a letter written by the United Chief Executive Officer Oscar Munoz, which was circulated to employees and later leaked on the social media and translated into Chinese.

Munoz made no apology for the way the passenger was treated and just emphasized that he had "refused to comply" with staff.