As part of their ongoing public relations clean-up campaign, United Airlines has offered refunds to all passengers onboard Flight 3411 from Chicago to Louisville.

"All customers on Flight 3411 from Sunday, 9 April, are receiving compensation for the cost of their tickets," United said in a statement.

United has struggled to preserve its image after videos of a passenger being forcibly removed from a flight sparked outcry on social media. The video showed police officers dragging doctor David Dao from his seat on the plane, while he and his fellow passengers protested loudly. Videos showed Dr Dao returning to the cabin with blood on his face. Passengers said he was removed to make room for United crew members on the overbooked flight.

Several of Dr Dao’s fellow passengers have jumped to his defence, accusing the police of using excessive force and the airline of racial profiling. Passenger Joya Cummings posted a video from the flight to Facebook on 12 April, along with the transcript of a voicemail she had received from United.

“We just want to call and reach out to you regarding your flight on 9 April [and] offer our apologies for the experience that you had with that…” a United representative says in the voicemail. “We are refunding your entire ticket for all three of you that were traveling.”

Ms Cummings said she was unimpressed with the airline’s response.

“This is a small gesture for the horror that everyone experienced on that plane and what the world is experiencing now at this injustice,” she wrote.

United CEO Oscar Munoz initially offered a brief statement on the event, apologising for having to “re-accommodate these customers.” As criticism escalated — and Untied stock prices plummeted — Mr Munoz issued a stronger statement saying the airline took “full responsibility,” and would “work to make it right.”

The CEO also appeared on ABC News on Wednesday to further his apologies.

"This will never happen again," Mr Munoz said. "We are not going to put a law enforcement official onto a plane to take them off … to remove a booked, paid, seated passenger. We can't do that."

Three officers from the Chicago Department of Aviation have been put on leave following the incident. The officers will remain on leave while investigators are “reviewing the details surrounding the incident,” department spokesperson Karen E Price told The New York Times.