A group of US businessmen have filed a lawsuit against American carrier United Airlines over the death of a giant rabbit during a flight from London to Chicago.

The lawsuit has been filed three months after the rabbit named Simon was found dead on April 20 and then cremated by the airline, the Associated Press reports.

The three businessmen bought Simon from a UK breeder with the intention of showing him at the Iowa State Fair, and then displaying him and selling related merchandise to raise money for the annual event, AP said.

Ten-month-old Simon reportedly measured 1.04 metres long.

The incident with Simon, a giant rabbit, is the latest unfortunate event to hit the beleaguered airline.

Simon, the offspring of Darius – who holds the Guinness World Record for longest rabbit –  had the potential to also grow to a record-breaking size.

Simon had been placed in a United Airlines kennel at Chicago’s O’Hare International Airport while awaiting a connecting flight to Kansas City, where his new owners planned to pick him up.

The lawsuit seeks unspecified damages to cover the costs of the rabbit as well as punitive damages.

It said United was negligent in the care and transportation of Simon and that the airline improperly cremated the rabbit, the AP reported.

Attorney Guy Cook, who represents the businessmen – Mark Oman, Steve Bruere, and Duke Reichardt – said they never intended to profit from the rabbit and that they planned to donate any money from the lawsuit to a state fair foundation.

“They’re frustrated with how United has handled this from the start,” Mr Cook was quoted as saying.

“None of them stand to benefit financially from the resolution.”

The lawsuit alleges United has a poor record of transporting animals, stating the airline accounted for a third of all animal deaths via US air travel in the past five years.

Simon’s father Darius was a world record holder. Photo: Pintinterest/Damien McFadden

The suit does not explain how the rabbit died, but puts forth several possibilities, including that it was exposed to low temperatures in the cargo compartment or that dry ice might have been left in the same compartment as the animal.

Before flying to the US, the lawsuit states, a veterinarian examined Simon and found him to be in “good physical condition and fit to travel”.

United spokesman Charles Hobart released a statement saying: “We were saddened by Simon’s death in April. We have received this complaint and are currently reviewing it.”

The lawsuit comes as United struggles to repair its image after a string of events, including the videotaped forced removal of a 69-year-old doctor from a plane at O’Hare International Airport and the banning of two young girls from a flight because they were wearing leggings.

United had the second-highest level of animal deaths and injuries of any US airline last year, or 2.11 per 10,000 animals transported, according to the US Department of Transportation. Only Hawaiian Airlines was worse at 3.99.

United transported 109,149 animals last year, second only to Alaska Airlines with 112,281.

– With agencies