Giant rabbit Simon, the central character in the latest public relations disaster for United Airlines, may have been frozen to death, according to reports. The pet died shortly after landing at O'Hare International Airport in Chicago on Monday (April 24).

Sources quoted by The Sun on Saturday claimed that the rabbit had been accidentally left in a freezer for as long as 16 hours following his flight. According to the newspaper, United was set to launch an investigation into who was responsible for 10-month-old Simon's untimely demise.

The source was quoted as having said: "The rabbit arrived fine but there was some sort of mistake and he was locked inside a freezer overnight.

"The next day staff went in and did an inventory. The rabbit was huddled up facing away from the front of the cage towards the wall.

The source added: "Everyone thought he was just having a nap or something. Nobody realised it needed to be taken out."

Though United Airlines' policy on domestic flights is that domesticated cats, dogs, rabbits and some household birds, may travel in-cabin, rules for international flights vary. Nonetheless Simon – who was set to become one of the world's biggest rabbits – would have been too big to fit in a permitted in-cabin kennel.

The source told The Sun since it was known that Simon had survived the flight and was alive and well once reaching Chicago, and his death must have taken place in the warehouse. Simon had been scheduled for a second flight to Kansas City where he was due to be collected for his new owner – a celebrity, who breeder Annette Edwards from Worcestershire declined to name.

However, United Airlines told The Sun the suggestion Simon had been accidentally frozen was "completely false". A spokesperson said: "Simon was cared for at the PetSafe kennel facility which is kept at room temperature (on average 70°F)."

It Is the second time this month United Airlines hit the headlines for unwelcome reasons after Dr David Dao was manhandled off an overbooked flight, leaving him with a broken nose, knocked out teeth and concussion. It was announced this week that Dr Dao had agreed an undisclosed financial settlement from the airline as a result of the incident.

giant rabbit
Simon, a 10-month-old continental rabbit (not pictured) mysteriously died on a United Airlines flight from London to Chicago. Photo by Sean Gallup/Getty Images