By Christian Smith 

Oscar Munoz, the CEO of United Airlines says that employees “followed established procedures” in an incident which saw a passenger dragged off a flight.

The flight was leaving from Chicago to Louisville on Sunday evening. Report says that there had been an overbooking and the airline made a request for four passengers to leave the plane to make room for four staff members.

Three people decided to take the offer, but a fourth man refused. A video footage circulating the internet, showed the man, said to be a Chinese American doctor, being dragged out of his seat by law enforcement agents.

The airline, which is America’s third biggest carrier has appologised. It plans to conduct a detailed review on the matter.

In a letter to staff, Mr Munoz said the passenger who refused to voluntarily leave the plane had been “disruptive and belligerent.”

Although he said he was “upset to see and hear about what happened,” the airline boss said staff where “left with no choice but to call Chicago Aviation Security Officers to assist in removing the customer from the flight.”

“While I deeply regret this situation arose, I also emphatically stand behind all of you, and I want to commend you for continuing to go above and beyond to ensure we fly right.”