United Airlines has been sued over the death of Simon, a giant rabbit who died en route from London to Chicago on 20 April.

Simon was found dead in a kennel at O'Hare Airport in Chicago following the journey. The rabbit had been placed in a United kennel while awaiting a connecting flight to Kansas City, where his new owners were set to pick him up.

The lawsuit, which was filed Wednesday (26 July) by a group of Iowa businessmen, seeks unspecified damages to cover the costs of the rabbit and punitive damages, CBS News reported. The three Des Moines-area businessmen who purchased Simon intended to show him at the Iowa State Fair.

Simon's new owners also planned to display him and sell related merchandise to raise money for the annual event.

According to CBS News, the owners said in May they were seeking the costs of buying and transporting the rabbit, an estimated $2,300 (£1750), as well as future earnings.

Attorney Guy Cook said the businessmen, identified as Mark Oman, Steve Bruere and Duke Reichardt, never intended to profit from the rabbit. The men plan to donate any money won in the lawsuit to a state fair foundation that funds the upkeep of the fairgrounds in Des Moines, CBS News reported.

The lawsuit claims United was negligent in the care and transportation of the rabbit and that it improperly treated the animal. It also alleges the airline has a poor record of transporting animals, noting the airline accounted for a third of all animal deaths via US air travel in the last five years.

United Airlines
United Airlines has been at the centre of a number of passenger-related controversies Justin Sullivan/Getty Images

"They're frustrated with how United has handled this from the start," Cook said. "None of them stand to benefit financially from the resolution."

In a statement, United spokesman Charles Hobart said: "We were saddened by Simon's death in April. We have received this complaint and are currently reviewing it."

The lawsuit does not explain how the rabbit died but provided several possibilities, including dry ice left near the animal or that it was exposed to low temperatures in the cargo compartment.

When the lawsuit was first threatened in May, Hobart said United reached "a satisfactory resolution" with Simon's breeder, Annette Edwards, in Worcestershire. However, the suit contents that Simon had been sold to the Iowa group, which had arranged and paid for the animal's transportation.

According to CBS News, the lawsuit seeks a jury trial in Des Moines. It is the latest high profile legal case United is involved in. In April, the airline forcibly removed a doctor from a flight to make room for more crew members.

The airline was also criticised for forcing a mother travelling with her two-year-old son to sit him on her lap after taking away his seat to give to another passenger.