US police have physically removed a woman from a Southwest Airlines plane after she told staff she had a life-threatening pet allergy, in the latest passenger scuffle to be captured on video and magnified on social media.

After she told the crew she was severely allergic to animals – there were two dogs on board – the woman was ordered to disembark because she could not show a medical certificate needed to stay.

The unnamed woman refused to leave the Baltimore-to-Los Angeles flight and the crew called police.

https://www.youtube.com/watch?time_continue=127&v=kyUiPcggHnc

“Our policy states that a customer (without a medical certificate) may be denied boarding if they report a life-threatening allergic reaction and cannot travel safely with an animal on board,” Southwest Airlines said in a statement.

“Our flight crew made repeated attempts to explain the situation to the customer, however, she refused to deplane and law enforcement became involved.”

Passenger and film producer Bill Dumas recorded the ensuing struggle between the woman and officers and posted it online.

The scene was reminiscent of an April incident in which security officers yanked a 69-year-old man out of his seat and dragged him off a United Express flight in Chicago, sparking a public outcry.

Southwest immediately apologised for the Tuesday night incident: “We are disheartened by the way this situation unfolded and the customer’s removal by local law enforcement officers,” spokesman Chris Mainz said.

The incident began quietly near the back of the plane, passengers said, as Southwest employees talked to the woman.

Mr Mainz said the airline offered to re-book her on a flight the next day but she declined.

In the video, a police officer pushes her from behind while another pulls her from in front.

“What are you doing?” she says.

“I will walk off. Don’t touch me!”

“All right, let’s walk. Let’s walk,” one of the officers answers.

The airline declined to give the passenger’s name. She could be heard identifying herself as a professor.

She told officers she needed to get to Los Angeles because her father was having surgery the next day.

Southwest does not notify passengers ahead of time about animals on board.

“In most cases, we can separate the animal from customer with an allergy,” Mr Mainz said.

“The onus is on the customer to tell us what their needs are.”